The dataTaker DT8x family of data loggers is extremely flexible, and they allow the measurement of pulse output sensors using several different methods. However, it is not always obvious which method should be used or which might provide the best results. This tech note is intended to provide some background on the techniques we have used to capture data from these sensors.

Sensor Signal Output Types

When choosing which to use, it is essential to know the electrical characteristics of the output pulses that are coming from the sensor. There are 4 common output types:

1. AC voltage output devices: These are not true pulse output sensors but are commonly found in anemometers and gear tooth magnetic pickup sensors. The signal output is an AC sine wave that varies in frequency and amplitude based on speed. In some cases, the voltage output can exceed 90 VAC peak-to-peak.

2. Dry contact devices: These are simple switches. This could be a mechanical switch (e.g., a micro switch or a reed switch) that is periodically closed, for example, by a magnet passing by (like on a door opening switch). In this case, the switch needs some sort of external excitation to generate a signal that can be measured by the data logger. A standard technique is to use a resistor (called a pull-up resistor) with one end connected to a voltage source and the other end connected to one side of the switch; the other side of the switch is connected to the ground of the voltage source.

3. Open collector output devices: These are very common in industrial automation systems and come in two flavors: NPN and PNP. In an NPN output, the emitter of a transistor is connected to the ground, so the output (collector) switches from on to off, effectively creating a series of open and closed connections to the ground as the sensor switches state. A PNP output is the opposite; the emitter is connected to the supply voltage, so the output switches between the open and the power supply voltage as the state changes. Like the dry contact switch, these sensors require an external source to create the pulse waveform. Proximity sensors are one of the most common types of sensors that use open collector outputs.                                           

4. Voltage Output Sensors: These sensors provide a true voltage pulse output. A common type uses TTL standard logic voltage levels; a low (off) is defined as a voltage below 0.8V, and a high (on) is a voltage above 2.0V. The output of these sensors can be fed directly into a digital input or counter circuit of the appropriate type. In industrial systems, you may find voltage outputs that switch between 0 and 24 VDC.

Data Logger Pulse Measurement Methods

The DT8x family of loggers offers 3 ways to measure a pulse output sensor s:

• Frequency measurement using an analog channel
• Low-speed counter using a digital channel
• High-speed counter channels

Each of these has certain advantages and disadvantages that make it more or less suitable for a particular sensor type.

1.  Frequency Measurement

Any of the analog input channels of the data logger can be used to measure the frequency of a repetitive pulse train using the “F” channel type. Internally, the logger has a very accurate time base reference that is used to measure the time between 2 zero crossings of the input waveform.

Figure 1 – Zero Crossing Measurement

By taking the inverse of this time the logger can calculate the frequency of the signal: f=1/(time between zero crossings)

An advantage of using the frequency measurement is that it can accommodate signals up to 50V p-p in series 4 loggers. To improve the reliability of the measurements, it’s best to set the logger to a fixed measurement range using the gain lock command, GLnnn. Also, the default settings allow measurement of a range of frequencies between 33 Hz and 20 kHz making this method suitable for fast pulses.
The main disadvantage of the frequency measurement method is that it relies on the voltage passing through 0.0V which has 2 implications:

a. In the case of a dry contact, open collector, or voltage output sensor, if the voltage does not pass through zero volts, i.e. the sensor switches from 0.5 to +5.0 volts, the frequency measurement will not be reliable. It is possible to work around this by using the reference offset option, 2V, with the F channel type which will apply an offset voltage to the measurement circuit to offset the crossing point to +2.5V.

b. The data logger may time out if the pulse frequency is too low, resulting in an “Under range” reading. The maximum time between zero crossings is 30 milliseconds but can be increased with a sample period as a channel factor option. However, this may affect the data logger’s ability to process other commands.

2. Digital Input Used as Counters

Any of the digital inputs 1D-8D (4D in the case of the DT82) can be used as a low-speed counter. Be aware that the first 4 digital inputs 1D-4D (or 3 inputs 1D-3D in the case of the DT82x) are electrically different from the remaining digital inputs, 5D-8D. The first 4 (3) inputs have a 47k ohm pull-up resistor to the internal 3.3V digital power supply. This makes them especially suitable for use with dry contact switches or NPN open collector sensors. The pull-up resistor will cause the digital input to go to a high voltage when the switch is open or the output transistor is off and will allow the input to go to 0.0V when the switch is closed or the output transistor is turned on. These channels are also compatible with sensors with a TTL output.

The other digital inputs have a 200k ohm pull-down resistor to ground. These inputs are well suited to PNP output sensors or the measurement of sensors that have a voltage output in the on state but are open in the off state. In the absence of an input voltage, the digital input will be 0.0 V or low, and when the sensor switches state, the external voltage from the sensor will cause the input to go high and increment the count. If it’s necessary to use these inputs with a dry contact or NPN output sensor, an external voltage source will be required to pull the input high to allow the data logger to count correctly.

As with the frequency measurement, there are several considerations when using digital inputs as counters.

a. The counters are implemented in software by scanning the digital inputs every 20 milliseconds to see if the state has changed. This means that the width of the pulse must be greater than 20 milliseconds or the logger may not detect the transition between scan times.
b. Based on the scan rate, a maximum measurable pulse frequency, assuming a 50% duty cycle, is about 25 Hz. Pulses of a higher frequency will not be properly counted.
c. When the data logger is asleep, the processor is in a low power state and the channels are not scanned so this method cannot be used to measure pulse counts over longer periods (the default is 30 seconds) when the logger is operating off battery or in a forced sleep mode which causes the logger to go into sleep mode between samples. If the low-speed counters need to be used continuously, the logger should be externally powered and the sleep mode should be disabled by setting parameter P15=2.

3. High-Speed Counter Controls

All of the loggers have 4 dedicated high-speed hardware counter channels (8 in the case of the DT85 S3/S4 models). These channels are capable of counting pulses as fast as 10 kHz. These channels are similar to digital channels 1-4 in that they incorporate a weak pull-up resistor that allows them to be used with dry contact or open collector output sensors as well as TTL output sensors. In addition, channels 1 and 2 can measure low-level signals from millivolt output sensors, such as those with an inductive pickup, using the low threshold (LT) option. This sets the off/on the threshold at <2 mV and >7 mV respectively.

The hardware counters will function if the logger is asleep allowing them to be used over longer sampling intervals however, the maximum count is limited by the width of the counter registers which is 16 bits equivalent to 65536 counts. If more pulses than this occur within the sample interval or if the count is allowed to accumulate over a long period it will overflow and restart back at 0. To prevent a loss of counts, configure the logger to read the high-speed counters frequently enough so that there will never be more than 65536 pulses within any sampling interval. For example, if the average counter input frequency is 100Hz then the DT80 must be programmed to wake at least every 65536/100 seconds (about every 10 minutes).

Also, when used with a dry contact (voltage-free) input where the input is not actively driven to a high state but rather is forced to a high by the internal pull-up resistor, the inputs are effectively filtered to “debounce” the input from contacts in mechanical switches or relays. This limits the maximum count rate to about 500 Hz when used with a voltage-free input.

Flow Meter Example

With all of this in mind let’s consider a common application of a water flow meter. A common turbine flow meter has a simple dry contact output that is triggered when a magnet embedded in one of the turbine blades passes by a reed switch. For this meter, a flow each gallon of flow produces 50 pulses. Therefore, a flow of 200 gallons per minute (GPM) produces 200 * 50 = 10,000 pulses in a one-minute interval or a frequency of 10,000 pulses/60 seconds = 167 pulses/second. For this application, it is necessary to record the flow every 10 seconds so our count for a 10-second interval would be 10 * 167 = 1670 pulse at a 200 GPM flow rate.

Since this sensor has a simple switch output and the pulse frequency is in the range of 100-200Hz, it is easiest to wire it to one of the high-speed counter inputs so let’s use counter 1.

In deTransfer the program would be:

BEGIN”JOB1”

CATTN

‘Spans and polynomial declarations

S1=0,200,0,1670”GPM”

‘Global declarations

RS1S

‘schedule definition

RA(“B:”,ALARMS:OV:100KB,DATA:OV:1MB)10S LOGONA GA

1HSC(R,S1,”Flow”)

END

Here, we have configured the scaling to take into account the 10-second sample interval by multiplying the sensor output by the interval, i.e. a flow rate of 200 GPM will produce 167 pulses/gallon x 10 seconds sample interval = 1670 pulses in the sample interval. Also, we have used the R option in the counter command to reset the count back to 0 after reading the count.

The setup in Delogger would be:

Note the resetting option has been enabled to reset the counter to 0 after each reading. It is not apparent, but the scaling has been adjusted per the previous example.

The setup in dEX would look like this:

The reset counter option has been enabled for this counter to reset the count to 0 after the measurement is made.

The scaling looks like this:

Conclusion

This article has provided an overview of measuring pulse outputs from various sensors using dataTaker DT8x data loggers. By understanding the four common pulse output types—AC voltage, dry contact, open collector (NPN and PNP), and voltage output—users can effectively match their sensors with the appropriate measurement technique. The article detailed three such techniques: frequency measurement, low-speed counting, and high-speed counting, highlighting the advantages and limitations of each. Careful consideration of sensor characteristics, signal frequency, and data logger capabilities is crucial for accurate and reliable data acquisition. We hope this guide helps you select and implement the optimal measure approach for their specific pulse output sensor application.

The post Reading Pulse Output with dataTaker DT8x Data Loggers appeared first on CAS Dataloggers.

The easiest to use non-encrypted service that we at CAS Dataloggers have found is SMTP2GO. This site offers a free service that provides 1000 free emails a month. When signing up for this service, the website (https://www.smtp2go.com) shows this as a trial, but there is no time limit to this trial, just a limit on the number of emails that can be sent.

All that is required for initial setup is an email and a password. See below for the screenshot:

Once you enter an email and a password, you will get an email with a link to click to verify the email. Once this is done, you’ll be able to log into the account and finish setup which will require you to either use the SMTP password provided or create a new one.

Here are the settings for the dataTaker (or other loggers) to use SMTP2GO:

• SMTP Server: mail.smtp2go.com
• Username: (Email address used to set up SMTP2GO account)
• Password: (Your chosen password. Not the password that is used to log into SMTP2GO)
• Port: 2525 (SMTP2GO offers several ports. 2525 seems to be the most reliable)

Configuration of a dataTaker DT8X Series Logger:

There are 2 pieces of software that can be used to access a dataTaker DT8X series logger. There is a version that runs under Adobe Air called dEX Desktop and one that does not require any Adobe runtimes called dEX 2.0. This setup guide will have screenshots for both software versions, but the basic setup remains the same.

To begin, we will show screenshots of the settings screens where the SMTP server information will be entered.

dEX Desktop

To access this screen, after connecting to the logger, click on “Configure the logger” and then click on the DT8X label at the top of the program column, which will take you to the settings window.

Click on the menu item “Ethernet Email.”

Enter the settings as detailed above in the appropriate text boxes.

Once these changes have been made, you will need to save the program to the logger by clicking on “File” and choosing “Save to Logger”

dEX 2.0

In dEX 2.0, once again, you will need to establish a connection with the dataTaker. Once the connection is established, you will need to click on the “Settings” icon, and then choose the “Communication” tab.

Under the “Communication” tab, select “Ethernet”

As stated above, enter the proper information into the “Email Settings” fields and click “Apply.” Once this is done, the settings have been made on the logger and you can then use email as either an alarm action or to send data.

For further information on using a Non-Encrypted SMTP Server with a dataTaker or other data logger device, or to find the ideal solution for your application-specific needs, contact a CAS Data Logger Application Specialist at (800) 956-4437 or request more information.

The post Non-Encrypted SMTP Server For Use With dataTaker And Other Devices appeared first on CAS Dataloggers.

CAS DataLoggers receives requests from manufacturers who need a data logging system to collect data for final test and quality assurance purposes. In some applications, they would like to tag the measured data with information like a serial number by scanning bar codes on products coming off of manufacturing lines. For these projects, we have used the dataTaker data loggers including the DT80, DT85 and DT82I models depending on the number of inputs required. These intelligent universal input loggers can capture a scanned bar code via the serial sensor port plus additional values like voltage or current to track product quality, performance or compliance to specifications. In this brief tech article, we’ll go through the steps needed to set this up.

Scanner to Data Logger Connection

For this application, we connect a barcode scanner, for example, the like the Zebra DS22 to their dataTaker’s serial port. The DS22 is a handheld wireless scanner that comes with a docking/charging cradle with a standard serial connector. This connector is normally used with a PC serial port or serial to USB adapter. To connect it to the data logger we build an adapter cable to go from the DB-9 female connector of the scanner to the serial port of the logger.

Scanner and Serial Port Configuration

The serial sensor port of the data logger is configured to match the serial port settings of the scanner, typically 9600 baud, 8 bits, no parity and 1 stop bit. Users then configure the barcode scanner so that whenever it scans a code, it appends a carriage return line feed to the serial string sent to the dataTaker. One very nice feature of the Zebra scanners is that they come with a set-up sheet that allows configuration of the scanner by simply scanning a barcode for on the setup instruction sheet.

Data Logger Configuration

While it is possible to have the logger periodically check to see if there is new data from the serial port, adding the carriage return to the serial string simplifies the programming. A very nice feature of the data logger is that it can automatically trigger based on the receipt of either any serial character or a specific serial string. So, the logger waits until it sees the carriage return and triggers a schedule to run. This schedule reads the serial characters sent by the barcode reader and saves them in a variable, either as a text string or numeric value depending on the type of barcode. Within this schedule, the logger can also take measurements of any other required signals; this can be a product’s temperature, battery voltage, pressure from a sensor or just about any desired set of values. All of the data, the barcode and any other values are recorded in the non-volatile memory of the data logger along with a time stamp.

In addition to collecting the measurements for history tracking, it is also possible for the data logger to compare them to preset limits to indicate if the product meets the quality specifications or is defective. Whenever a value falls outside these limits, the data logger can generate an alarm, either locally via a digital output or remotely via an email or text message. The digital output can also be connected to an alarm light, siren, or other external contact warning device. The alarm information is also stored in a separate data store so it’s possible for users to pull the data at the end of the shift, day or batch to get a list of all failed products by their barcodes.

Benefits of dataTaker Loggers

The dataTaker loggers save time and improve the quality of reporting data. First, they remove the need to purchase additional devices; both captures of the barcode information and measurement of product performance can be done with a single device. There is no need to have one device to read the part serial number information and a second device to measure electrical data and then try to paste it together. Data quality is improved by automatically collecting everything at once, there is no worry about making sure that the measured data is for the correct part or problems with manually recorded data.

The free programming software included with every dataTaker logger makes set-up a snap. Also, recorded data can be viewed in mimics, trend charts, or tables, and users can also download historical data for analysis. These intelligent input data loggers allow connection to a wide range of sensors and data measurement sources to measure almost any signal including temperature, humidity, voltage/current, 4-20 mA loops, resistance, and many others. They also offer extensive communications capabilities including Ethernet, USB, Serial and cellular models.

These advanced features make dataTaker data loggers an ideal solution for real-time data acquisition, remote monitoring, and control needs. World-renowned for their robust construction, our dataTakers are built to last even in the face of extreme natural and industrial environments and years of nonstop use.

For further information on dataTaker Data Loggers, barcode scanners or to find the ideal solution for your application-specific needs, contact a CAS DataLogger Application Specialist at (800) 956-4437 or request more information.

The post Using a dataTaker Data Logger with a Barcode Scanner appeared first on CAS Dataloggers.

Winlog Lite SCADA Software enabling a wide range of application development and online browser-based access. Factory and plant managers can benefit from using a dataTaker DT8X Series Data Logger to create and configure their Winlog Lite projects.

Winlog Walkthrough:

1. Prerequisites:
   • Apps Note: ‘Connecting a dataTaker DT80 Range Data Logger to an Ethernet Modem‘
2. Requirements:
   • dataTaker DT8x datalogger running firmware V 7.12 or above
   • PC with Winlog Lite installed (available from sielcosistemi.com)
   • dataTaker DeTransfer software
   • Network connection between the PC and the dataTaker
3. Method

   • 3.1 Check dataTaker settings

Write down the dataTaker MODBUS_SERVER and ETHERNET profile settings. These contain the information that you’ll need to communicate via Modbus RTU TCP. If you are using an automatic IP address, then you should consider changing this to a static IP address—consult your network administrator about this.

When using Modbus, the values are transmitted in integer (whole number) form. This means that the values are all rounded to the nearest whole number. To maintain decimal precision, you can specify a scale factor for the numbers transmitted over the Modbus connection, then divide the value on the receiving end. This is done via the SETMODBUS command.

To scale the dataTaker’s channel variables 1-30 by 100 (which would give you 2 decimal places), you would enter the following dataTaker command: SETMODBUS 1..30CV MBI 100.

Note that when using the MBI format, the valid range is -32768 + 32767, hence if you use a divider of 100, then you must have values between -327.68 + 327.67.

3.2 Create and set up a Winlog Lite project

Open up the Winlog Lite ‘Project Manager’ by clicking [Start] Programs Winlog Lite Project Manager
Click the ‘Create new project’ button
Give the project a name and Click ‘OK’ The project shall now appear in the project tree.
In the project tree, expand the project that you just created and click Configuration, then double-click Channels
In the Channels configuration window, select Modbus RTU TCP from the drop-down. The Options window should now appear.
In the options window, change the Port number to the value of the TCPIP_PORT parameter in your dataTaker and add the IP Address of your dataTaker to the IP address list. Click OK to close the options window, then OK again to close the channels configuration window.
Double-click Devices.
Click Add, the New device dialog will appear. Use the default Channel and Device settings (1,1) and enter a description for your device. Click OK to close the dialog, then OK again to close the devices window

3.3 Adding Measurements (Gates) to the Project:

In the project tree, click Gates then double-click Numeric.  The Gate Builder window will appear.
To add or modify a gate, double-click on a blank or gate line. This opens the Gate Properties window.
On the General tab, the essential properties which  must be defined include: Gate ID – name your gate N ID – a number for your gate Description
On the Sampling tab, choose the Channel and Device to be 1. The Address is mapped to the channel variable you wish to view, but is 30,000 minus one (40,000 if you need to read/write). i.e. if you wish to view 23CV then you enter address 30022Change Sample to ‘Always’ and define your sample frequency
On the Value tab, enter the Maximum and Minimum values for your variable Change the Variable Type to S_WORDEnter the number of Decimal Digits you will use (this is to counter the scaling performed when setting up the dataTaker)
On the Conversion tab, select ‘Apply decimal digits conversion’. You may leave the rest of the fields as default Click OK to finish and add your gate Save the changes on the Gate builder window and close

3.4 Creating a Template/Dashboard

In the project tree, click Template Right-click in the blank space and select New File A file with the name ‘No Name’ will appear Double-click the No Name file to open it. The Template Builder will appear.
In the template window, you can choose a range of different controls and images to place on your dashboard.
Place the controls on the template, insert buttons, gauges, pictures, charts etc. Remember to save the template as you build it up.
To assign variables to your controls, click on the Gates option in the property editor, on the left of the screen. Follow the prompts to add your gates to the list.

Once you have completed adding components to your dashboard, save your template and choose the template window.

3.4 Executing Your Template/Dashboard

To run your dashboard, open the Project Manager and right-click on the project name and select Execute.

Once the project opens, click Supervision, Template, Template name. If you would like a template to automatically open whenever you execute the project, you can follow this procedure.

First, let us make the current project the default. To do this, right-click on the project name and then click Default. Now the project will have a green border around its icon to indicate that it is the default project. Now, the project can be executed from the start menu under: [Start] Winlog Lite Runtime
In the project tree, click Configuration Template
The Available Templates list can be seen on the left. From this list, double-click the template you wish to open at startup. This will transfer it to the Selected Templates list. Click OK

For further information on the Winlog Lite SCADA Package with DT80-Range Data Loggers or for additional technical support, contact a CAS Data Logger Technical Specialist at (800) 956-4437 or request more information.

The post Using the Winlog Lite SCADA Software with a DT80-Range Logger appeared first on CAS Dataloggers.

At CAS DataLoggers, many of our callers want to see how often one or more of their machines are operating and when. This pinpoints machine downtime and can identify poor work productivity, or identify if another cause is at work (power outages, etc.) In our latest Technical Article, we outline how to configure a Series 4 dataTaker DT8x Data Logger for runtime monitoring. What is the downtime? Downtime can be defined as periods of inoperability when a machine or device is not operating. This can be different from simply powered on and can be triggered by an electrical switch, rotation, or some other measured parameter on the machine.

There can be many different causes of machine downtime. These causes of downtime include:

Workstation starve – when there is no material or part available on which to operate

Workstation block – when the output of the machine is blocked by the last finished part

Failure or fault – when the machine has an active fault or failure

Power outage – when there is no operating electric power, pneumatic air, or hydraulic pressure

Personnel issue – no operator available

If suitable sensors are available to determine which causes exist, this can also be logged.

Configuring the dataTaker

While most basic data loggers typically don’t get into this level of functionality, there are many models of intelligent devices that can monitor runtime and more complex applications. For runtime monitoring, these data loggers and data acquisition systems feature one or more digital channels.

To configure the dataTaker, users define CVs (Channel Variables) in the dataTaker’s built-in dEX software. A channel variable is a memory location (or register) in the dataTaker’s operating memory used for holding or manipulating data or state. Defining CVs enables users to automate data collection and control features.

Using a dataTaker DT80 intelligent data logger, the logger’s configuration reads machine-run data using the logger’s two digital inputs. Our program shows how to set up a few simple calculations of machine runtime and On/Off events. Our data logging schedule runs every second, taking a sample from the DT80’s Digital Sensor Channels 1 and 2.

Defining the Schedule

Schedule 1 shows example data and code to add this functionality. It consists of:

• Counter1_1State: Code = 1MODBUS(“Machine1Power”, AD11, R4:9,=1CV) (This line returns a 1 or 0 value for Channel 1 to indicate if the machine is currently running, i.e. its On or Off status).
• Counter 1_2State: Code = 1MODBUS(“Machine1Move”, AD11, R4:10,=11CV) (This line returns a 1 or 0 value for Channel 2 showing if the machine is currently on or off).
• Counter1_1OnTime: Code = IF(1CV>0.5){2CV=2CV+1} (This line gives the duration of time that the machine has been on, measured from the last recorded sample)
• Counter1_2OnTime: Code = IF(11CV>0.5){12CV=12CV+1}

Totalizing Run Time

Our dataTaker has also been programmed to calculate and display the Total Machine Run Time. Every night at midnight, the data logger generates runtime cycle totals and runtime totals for that day. This data is given as ‘PreviousDay1_1On’ and also as ‘PreviousDay1_1Off’, and for runtime, it is ‘PreviousDay1_2On’ and ‘PreviousDay1_2Off’. This allows users to compare runtime across many different days to spot trends.

Meanwhile, the calculations are named Machine OnTime, OffTime, MoveTime, and NoMoveTime. All are expressed in seconds.

When it generates these daily totals, the dataTaker also resets all counters, having been programmed to do this so that it can count the new day’s total from zero. The code to reset all these values is:

• 2CV(W)=0
• 3CV(W)=0
• 12CV(W)=0
• 13CV(W)=0

For further information on runtime monitoring using dataTaker data acquisition systems, or to find the ideal solution for your application-specific needs, contact a CAS Data Logger Application Specialist at (800) 956-4437 or request more information.

The post Runtime Monitoring Using a dataTaker Data Logger appeared first on CAS Dataloggers.

Equipment Required for Water Level Monitoring:

• dataTaker DT8x data logger
• Druck PTX 1830 depth sensor
• Wire

1. Connecting the sensor:

Connect the wires from the sensor to the datalogger as follows:

• Red Wire–12V terminal
• Blue Wire—Channel 1 # terminal
• Connect a wire between DGND and EXT# terminals

2. Taking measurements:
   • Basic measurement:

The basic measurement outputs a scaled output. Using the built-in dataTaker dEX software, the code is as simple as this:

S1=0,10″m”    ‘scale a 4-20mA reading to a 0-10m value

1SSPWR=1                ‘turn on the 12V output

1#L(“depth~m”,S1) ‘sample, scale and log depth

• Full Program:

The full dataTaker dEX program samples the sensor once per hour and stores it to the datalogger internal memory.

BEGIN “PTX1830″

‘Sample program Level sensor PTX 1830 (4-20mA)

‘Sampling period: 1 sample / hour

S1=0,10″m”    ‘set scale of 4-20mA sensor

LOGON

‘====================================================

‘ Schedule A

‘ – Logs to the internal memory (B:)

‘ – Logs up to 3MB of data records, overwrites when full

‘ – Runs every 1 hour

‘====================================================

RA(“B:”,DATA:OV:3MB)1H

‘control power and sample from the sensor

1SSPWR(W)=1 1#L(“2-Minute Depth~m”,S1,MD5000,FF3) 1SSPWR(W)=0

END

Using the dEX graphical configuration software, built into every dataTaker, you can configure the same operation with a few mouse clicks and entering a few numbers.

DataTaker Series 4 Loggers:

The renowned dataTaker Series 4 Dataloggers can connect to nearly every sensor type, scaling and logging almost any physical value including Temperature, Voltage/Current, 4-20mA loops, Resistance, Strain gauges, Frequency, and more. They also provide a wide array of communications features including USB, Ethernet, MODbus, and SDI-12.  dataTaker loggers also feature a USB memory stick port to give you simple access to the stored data when no communications options exist.

dataTaker’s dEX software is preinstalled with all dataTaker dataloggers and has a browser accessed graphical interface allowing quick setup and configuration of the logger. This software is configured and run directly from a web browser enabling access either locally or remotely over the Internet. Operators can use either USB or Ethernet to connect to the datalogger and access the dEX application.

For more information on Series 4 dataTaker dataloggers for water level monitoring, or to find the ideal solution for your application-specific needs, contact a CAS Data Logger Applications Specialist at (800) 956-4437 or request more information.

The post Water Level Monitoring Using a Druck Depth/Level Sensor appeared first on CAS Dataloggers.

Smart data loggers offer several convenient features, not least of which is the ability to connect to local area networks (LANs). In our latest Technical Article, CAS DataLoggers and dataTaker show you how to connect a dataTaker DT80-range intelligent logger to a LAN. It’s an easy way to enable quick data retrieval and data sharing.

Prerequisites:

• Nil

Required Equipment:

• dataTaker DT80 Range Data Logger
• Ethernet cable
• Free network port on an active wall-plate, switch, router, etc.
• PC with free USB port and DeTransfer software (static IP address only)

Process

Physical Connection:

1. Apply power to the dataTaker

2. Plug one end of the Ethernet cable into the dataTaker and the other end into a free, active Ethernet port (wall plate, router, switch or hub) so that the dataTaker is connected to the network. Ensure that both plugs ‘click’ firmly into their sockets.

3. Now that the dataTaker is plugged into the network, it needs a network (IP) address.

• If the network supports dynamic IP addressing, then you must configure the IP settings of the dataTaker manually: proceed to the “Static IP addresses” section.
• If the network doesn’t support dynamic IP addressing, then you must configure the IP settings of the dataTaker manually: proceed to the “Static IP addresses” section.

Obtaining an IP Address

Dynamic IP Addresses: If the network has assigned the logger an IP address, then it will be displayed on the “Eth IP” screen (on the dataTaker) as shown above (use the UP/DOWN arrows on the front of the logger to navigate to this screen).

NOTES:

1. • If the IP address is displayed as 0.0.0.0, then the dataTaker is still looking for an IP address.
   • If the IP address instead begins with 169.254, then the data logger has assigned itself an IP, not the server. In this case a static IP address must be used.Once the logger has successfully been assigned an IP address, you will be able to browse to the dataTaker web interface using any web browser

Static IP Addresses:

To assign a static IP address, just follow these steps:

1. 1. Obtain TCP/IP settings from the network administrator. You’ll need an IP address, subnet mask, gateway, and DNS server addresses.
2. Plug the USB cable into the USB slave socket on the side of the dataTaker, and the other end into a PC.
3.  Using DeTransfer software, establish a connection to your dataTaker.
4. Now enter the following commands into the command window:

PROFILE”ETHERNET””IP_ADDRESS”=”XXX.XXX.XXX.XXX”
PROFILE”ETHERNET””SUBNET_MASK”=”XXX.XXX.XXX.XXX”
PROFILE”ETHERNET””GATEWAY”=”XXX.XXX.XXX.XXX”
PROFILE”NETWORK””DNS_SERVER_1″=”XXX.XXX.XXX.XXX”
PROFILE”NETWORK””DNS_SERVER_2″=”XXX.XXX.XXX.XXX”
(Where XXX.XXX.XXX.XXX are provided by the network administrator.)

5. You’ll be able to check the IP address at any time by looking at the “Eth IP” screen on the dataTaker as shown above (use the UP/DOWN arrows to navigate to this screen).

Once you’ve successfully entered the TCP/IP settings, you’ll be able to browse to the dataTaker web interface just by typing the address into a web browser.

For more information on connecting a dataTaker DT80 Range Data Logger to a LAN, contact a CAS DataLoggers Technical Specialist at (800) 956-4437.

The post Connecting a dataTaker DT80-Range Data Logger to a LAN appeared first on CAS Dataloggers.

The dataTaker supports two methods of Wheatstone bridge measurement:

• excitation of sensors using a constant current source
• excitation of sensors using a voltage source

Both of these methods of bridge support can have a number of options, depending on the number of active arms in the bridge and the number of wires used to connect bridges to the dataTaker data logger.

Constant Current Excitation of Bridges

The constant current excitation method of bridge measurement utilizes a current of 2.500 mA or 200.0 μA for excitation. The advantage of using this method is that the bridge sensitivity and zero offset is independent of the length of leads used to connect the bridge to the dataTaker, so this method is particularly useful if long lead wires (25 feet or greater) are used to connect the logger to the sensor. In some cases, the bridge output can have greater linearity and reduced temperature sensitivity for constant current excitation than for voltage excitation.

The bridge excitation current is supplied between the Excite (*) terminal and the Return (#) terminal of the analog input channel during measurement. Note that the current is only applied for approximately 50 milliseconds so it will be difficult to measure using a standard meter. The current is applied for approximately 10 milliseconds before the bridge voltage measurement is initiated. In the case of long cables which might have significant capacitance, this delay can be increased using the MDn channel option where n is the delay time in milliseconds. By default, the bridge excitation current is 2.500 mA but may be set to 200.0 μA if required. The 2.500 mA current provides the best resolution for typical 350-ohm strain gauges, but the smaller current can be used if the strain gauge resistance is greater than 700 ohms or if the self-heating of the bridge sensor is a concern. If the 200.0 μA excitation current is required, then this is specified as a channel option in the channel specification using the I channel option.

The Arm Resistance

The data that is returned by the data logger from bridge circuits excited with a constant current is the ratio of the change in arm resistance to the nominal arm resistance. The data is returned in units of ppm (see below). The arm resistance for the bridge being measured must be known by the dataTaker and is specified as a channel option in the channel specification. The default arm resistance is 350 Ohm, which is typical for many types of strain gauges. For higher accuracy, if the actual arm resistance is available from the data sheet or if the bridge resistance is not 350 ohms, the arm resistance can be specified as a channel option Ohms.

Full Bridge with Constant Current Excitation

The dataTaker can provide excitation and measure the output from a full bridge of devices such as strain gauges, pressure cells, load cells, etc. This configuration is a 4-wire input and supports 1, 2, or 4 active arms. Any of the bridge arms can be active arms. The configuration also provides compensation for cable wire resistance, allowing long cable wires to be used. Bridge arms that are not active must have bridge completion resistances. These can be inactive devices of the same type as the devices on the active arms, or these can be a resistor with the same resistance value as the active devices at rest, and ideally have a temperature coefficient that is similar to that of the active devices. The entire bridge circuit is external to the dataTaker – the logger does not provide any bridge completion for partial bridges. The full bridge configuration with constant current excitation is connected to the dataTaker as a 4-wire input:

where the Excite terminal provides current excitation of 200.0 μA or 2.500 mA, which returns via the Analog Return (#) terminal. The bridge output is read between the + and – terminals.

Interpreting the Data from a Full Bridge with Current Excitation

The data returned from full bridges is the ratio of change in measured resistance to the arm resistance, expressed in parts per million as follows:

Where:

• Vm is the measured voltage
• I is the excitation current
• Rarm is the nominal arm resistance

Calculating Microstrain for Full Strain Gauge Bridges

When using stain gauges in full bridges, it may be desirable to convert the returned data from units of ppm to units of Microstrain. This can be done by the following formula:

Half Bridge with Constant Current Excitation

The dataTaker can also provide excitation and measure the output from a half-bridge configuration of strain gauges, pressure cells, etc. This configuration is a 3-wire input that supports 2 active arms. This configuration compensates for cable wire resistance and temperature difference. The half-bridge configuration with constant current excitation is connected to the dataTaker as a 3-wire input.

In this case, Ra and Rc are the 2 active arms of the half-bridge. Note that a jumper is required between * and + terminals. As before, the result of the measurement is returned in ppm which is the effective change in resistance of the bridge multiplied by 106. When using stain gauges in half bridges and current, it may be desirable to convert the returned data from units of ppm to units of Microstrain. This can be done by the following formula:

or

This half-bridge method of strain gauge measurement has a measurement resolution of approximately 0.2 Microstrain.

Quarter Bridge with Constant Current Excitation

The quarter bridge configuration for measuring bridges is a variation of the half-bridge configuration, where there is one active device (such as a strain gauge) and a bridge completion resistance to balance the bridge. The bridge completion resistance can be an inactive device of the same type as the active device or can be a resistor with the same resistance value as the active device, and ideally has a temperature coefficient similar to that of the active device. The entire bridge circuit is external to the dataTaker – the logger does not provide any bridge completion for partial bridges. Quarter bridges with constant current excitation are connected to the dataTaker as follows:

In this case, Ra is the active arm of the quarter bridge and Rc is an external bridge completion resistor. Note that a jumper is required between * and + terminals. As before, the returned value is:

In this case, for accurate results, it is important that the bridge completion resistor Rc have a resistance that is equal to the active arm of the bridge at rest to properly balance the bridge (measured voltage =

0.0 with no load applied). To convert data from units of ppm to units of Microstrain, the standard formula becomes:

Voltage Excitation of Bridges

The alternative method for measuring bridge circuits with the dataTaker is voltage excitation with ratiometric measurement. The principle of the method is that the bridge is excited by a constant voltage source and the bridge output voltage is measured as a ratio of the measured voltage to the excitation voltage. In practice, the resistance of the cable wires connecting the bridge to the logger reduces the excitation voltage that is actually applied to the bridge, which in turn results in a proportionate loss of output signal voltage from the bridge. To correct this error, the actual voltage applied across the bridge is measured using a second channel.

The Bridge Excitation Voltage Source

The bridge excitation voltage, also often referred to as the bridge power supply, can be supplied from a number of sources:

• the internal voltage excitation source of the dataTaker via the Excite (*) terminal of the analog channel, which can output a nominal 5 Volts (actually nearer 4.5 Volts);
• the switched 12 Volt sensor power supply terminal of the dataTaker, which is limited to 100 mA total current draw;
• the switched 5 Volt sensor power supply terminal of the dataTaker (Series 3 only) which is limited to 25 mA total current draw;
• or an external voltage source either directly connected to the bridge or switched through the EXT */# terminals.

The bridge excitation voltage must be switched on during the period of measurement. If the internal voltage excitation source is used, it will be automatically switched on by the logger at appropriate times. If an external voltage source is used for excitation, the bridges can be either permanently powered or can be powered only during measurement by using the external excitation terminals of the data logger. The default for the internal voltage source for bridge excitation is the unregulated 5-volt supply from the Excite terminal and is automatically selected when bridge inputs with voltage excitation are specified. However, if the bridges are powered from external sources connected directly to the bridge, then the Excite terminal voltage should be disabled using the N channel option. If the bridge is to be powered from external sources connected through the external excitation terminals, EXT */#, then the external excitation option should be enabled using the E-channel option.

Measuring the Bridge Excitation Voltage

In practice, the resistance of the cable wires connecting bridges to the dataTaker reduces the excitation voltage that is actually applied to the bridge. This results in a proportionate loss of output signal from the bridge. To correct this error, the actual excitation voltage across the bridges is also measured. The bridge excitation voltage is connected as a differential or single-ended voltage input to any analog input channel and must be measured immediately before the output of any bridge is measured. This measurement is referred to as the ‘bridge reference voltage’, and is measured on the bridge reference channel that is identified to the dataTaker by the BR channel option for the particular channel. This can be on the same channel as that being used for the actual bridge signal voltage or on a different channel.

Note that if the excitation voltage is greater than 3.0 volts, it might seem possible to use the HV channel type to measure the bridge excitation voltage, but this is not recommended since the measurement accuracy when using this channel type is normally not sufficient for bridge applications. In this case, it is better to use the bridge itself to attenuate the voltage being sourced and then use a scale factor to allow the data logger to calculate the actual excitation voltage.

To measure the excitation voltage in dEX, use the appropriate channel in the channel wiring screen or use Manual Channel Type with the following commands:

Notes:

1. The bridge reference channel must precede the bridge measurement channel(s) in the dataTaker program because the bridge reference voltage is used to calculate the bridge data for the subsequent bridge measurement channels.

2. If bridge measurements are included in more than one Schedule, then the bridge reference channel(s) must be declared in each Schedule.

3. If a bridge reference channel is not declared, then the bridge reference voltage defaults to 5 Volts.

Full Bridge with Voltage Excitation

The full bridge with voltage excitation configuration is the more traditional method for the measurement of bridge outputs. However, fully implementing this requires more resources than any of the constant current methods, requiring two channels for each bridge if each bridge has a separate bridge excitation. If a shared excitation source is used, two channels are required for the first bridge, with one channel for each additional bridge that is excited by the same power supply. This configuration is only appropriate if all cable wires are the same length, such that all bridges receive the same voltage excitation as measured for the first bridge. This configuration supports 1, 2, or 4 active arms. Any of the bridge arms can be active arms. Bridge arms that do not have active devices must have bridge completion resistances to balance the bridge. These can be inactive devices of the same type as the active devices or can be a resistor with the same resistance value as the active devices at rest, and ideally have a temperature coefficient that is similar to that of the active devices. Also, the entire bridge circuit is external to the dataTaker – the logger does not provide any bridge completion for partial bridges.

Interpreting the Data from a Full Bridge with Voltage Excitation

Data returned from full bridges with voltage excitation is calculated as the ratio of the change in bridge output voltage to bridge excitation voltage, expressed in parts per million as follows:

Calculating Microstrain for Full Strain Gauge Bridges

When using stain gauges in full bridges, it may be desirable to convert the returned data from units of ppm to units of Microstrain. This can be done using the following formula:

This full bridge method of strain gauge measurement has a resolution of approximately 0.2 Microstrain.

Half Bridge with Voltage Excitation

Half bridges with two active arms and voltage excitation are commonly used when a large number of bridges need to be located in close proximity. The dataTaker supports this configuration by using single-ended inputs. Half bridges with two active arms require two bridge completion resistances to balance the bridge. The two bridge completion resistances can be either inactive devices of the same type as the active device or can be a resistor with the same resistance value as the active devices, and ideally have a temperature coefficient similar to that of the active devices. This half-bridge configuration with voltage excitation can be used to measure a single half-bridge or to measure a number of half-bridges that share the same bridge excitation voltage supply, and share the same set of bridge completion resistors. Multiple half-bridges that are excited from a single excitation voltage source and that share bridge completion resistors are illustrated below.

Interpreting the Data from a Half Bridge with Voltage Excitation

Data returned from half bridges with voltage excitation is calculated as the ratio of the change in bridge output voltage to bridge excitation voltage, expressed in parts per million as follows:

Calculating Microstrain for Half-Strain Gauge Bridges

When using stain gauges in half bridges, it may be desirable to convert the data from units of ppm to units of Microstrain. This can be done via the standard formula:

Converting Bridge Outputs to Engineering Units

So far, methods have been provided to convert measured bridge output in ppm to units of Microstrain for the various bridge configurations. However, units of Microstrain apply to strain gauge bridges which

are measuring deformation. Many sensors available today employ a bridge circuit to sense the parameter they are designed to measure. For example, some pressure cells, load cells, micro-displacement transducers, etc. in fact contain a diaphragm or similar structure which has a full strain gauge bridge bonded to one surface. The diaphragm is mechanically distorted by the pressure or load, which is measured by the strain gauge bridge. This distortion is calibrated to units of pressure, load, etc. by the manufacturer. Supporting these types of sensors with the dataTaker is quite simple, as shown by the following examples.

Pressure Transducer

A pressure transducer that is constructed as a full bridge device with a 4-wire connection, is connected to the dataTaker as a full bridge with constant current excitation (type BGI). The transducer has an output of 0.05 V full scale at 10 VDC excitation for a full-scale pressure of 100 PSI. The dataTaker will measure:

At minimum bridge output (0.0 psi) = 0.0 ppm

At full-scale output = 5000 ppm at 100 PSI

Therefore 1ppm = 100 PSI/5000 ppm = 0.02 PSI. This transducer calibration can be used in a dataTaker program to return the data in units of PSI so that it is a simple matter of constructing a scaling conversion to convert ppm to PSI.

Load Cell

A load cell that is constructed as a full bridge device with a 4-wire connection is connected to the dataTaker as a full bridge with constant current excitation (type BGI). The load cell measures a load of 100 lbs full scale and has an output of 2.0006 mv/V at full scale. The dataTaker will measure:

At minimum bridge output (0.0-pound load) = 0.0 ppm

At full-scale output = 2000.6 ppm at 100-pound load

Therefore 1 ppm = 100 lbs / 2000.6 ppm = 0.049985 lbs. This transducer calibration can be used in a dataTaker program to return the data in units of lbs.

Measurement Ranges and Accuracy

The dataTaker measures all bridge inputs as a low-level voltage, with a resolution of 0.25 μV, and a nominal accuracy of 0.1%. The accuracy for particular applications can be calculated from this information and the excitation current or voltage used.

Error Messages

There are no specific error messages for bridge inputs. However, input voltage signals which fall outside the voltage range of the dataTaker will produce an over-range reading of –99999.9 ppm or +99999.9 ppm. The dataTaker also reports the error condition with the error message ‘E11–input(s) out of range’ if the Messages Switch /M is enabled.

The post Strain Gauge Measurements With Current appeared first on CAS Dataloggers.

SQL Database Allows Users to Parse Data Using Filters

At CAS DataLoggers many of our callers want an automated method to transfer the data from a data logger into a SQL database so they can easily track and parse the data using filters, create reports and charts, etc. SQL is much more functional than many other databases such as MS Excel, especially when it comes to viewing a large volume of files, say over a period of two years.

DataTaker data loggers can accomplish this using FTP (File Transfer Protocol) to push all the data they record to an FTP server. We’ve created a program that, whenever it sees a new file, tells the dataTaker to place it directly into MS Sequel. This way, all files are in a convenient database where users can quickly search for data by time, temperature, etc. In our latest Tech Note, we detail how to export your collected data from a dataTaker into a Sequel database.

Data Logging Schedules:

In the dataTaker logger we have two logging schedules.

• The first schedule tells the data logger to read 4 separate thermocouple sensors once every 30 seconds and to save the data.
• he second schedule runs once every 6 hours and grabs any and all new data that have been saved from the first schedule, pushing it to an FTP server.

This functionality is already built into the logger via dEX software.

In summary, our data logging schedules are commanding the dataTaker to record 4 temperatures every 30 seconds and 6 hours. When the file is created, its filename format is .csv. In our example we’ve used FileZilla, a free FTP server available online.

Note: We’re saving the data in CSV format, i.e. a text format, so be aware that in the image below, we’ve set the data format in the data logger so that it’s sending the time as integer seconds. This is because databases don’t easily deal with fractional seconds.

Data Transfer via FTP:

FTP bundles the collected data from the data logger and sends it to the server. After the server responds, FTP logs on and then sends the data in chunks. FTP also has features within the standard to verify that data is transferred, including filename extensions which we’ll cover below. FTP is also popular for its built-in security and redundancy features.

FileZilla grabs all the data and stuffs it into a local directory, uploading it to an upload folder. In our application this is all done by Ethernet.

There are two pieces of software running here:

1. Windows Batch File: When it runs, this application checks to see if there’s a new .CSV file in the Upload Folder. When it sees one, it creates a new file called Import Data. Windows Batch File then makes a copy of the file and tells Sequel to load it into the Sequel database. When done, it names the file based on whether or not the file was successfully uploaded (see below for detail on the .bak and .bad file extensions).
2. Windows Task Scheduler: See below

Sequel Import:

We created a database file named ‘Daq’ based on a Sequel command called BulkInsert. When it receives the BulkInsert command, Windows Batch File grabs data from the CSV file and loads it into the SQL database, using a format file to create the ‘Daq’ file. It does this using an SQL format command, in this case ‘SQLCHAR.’

Inside Daq, we created a table called ‘DaqData’. This table has 5 items in it to track the time stamp along with the 4 temperature values from the thermocouples. See the image below.

This dataTaker capability makes it easy for users to filter their data and present it however they want. It’s especially useful for parsing data from one or more years’ worth of readings. For instance, in SQL you can run Queries to parse the data, or charting, or 3rd-party reporting, etc.

Automated Setup with Windows Task Scheduler:

While users can execute the ‘ConversionLoop’ Batch File manually, it’s more convenient to automate this process using the Windows Task Scheduler. We do this by using the Task Name ‘Upload to SQL.’

For example, in our setup, the Task Scheduler is programmed to run every 10 minutes to see if a new file is there. If so it runs ConversionLoop and imports the file(s) to SQL.

The last function that ConversionLoop performs occurs once it’s successfully opened the CSV file. It either:

• Renames the file with the extension .bak (indicating that the data is backed up).
• Or renames it with the extension .bad (indicating that the data is not backed up).

For more information on how to export data from a dataTaker to a sequel database, contact a CAS DataLoggers Technical Specialist at (800) 956-4437.

The post How to Export Data from a dataTaker to a SQLDatabase appeared first on CAS Dataloggers.

Series 3 dataTaker dataloggers are popular for their communications functionality and for their ease of programming using the built-in dEX software. In our latest Technical Article, we show you how to assign password protection to your dataTaker DT80 series logger and how to limit access to its interface if desired.

1. Setting Changes (in dEX Software)

NOTE: The changes specified in this document require your logger to be running firmware version 9.08 or above. You can update to the latest version on our dataTaker downloads page.

If your data logger was configured using dEX, then the security settings are all located in the Security tab (click on the model # at the top of the tree, then on the Security tab).

1.1 Password Protect the inbuilt FTP Server

The FTP server is one of the two key methods for changing settings on your dataTaker data logger. The most important change when locking down the dataTaker web services is to prevent unauthorized access to this server. The recommended action here is to change the default FTP username and password and to disable anonymous access.

1.2 Password Protect the Command Port

Adding a password prevents your data logger from accepting unauthorized commands. Once a password is set and the user is signed off, the dataTaker will not respond to commands. To access the command interface on a password-protected logger, you must type the password and then press Enter. The command window is available within in the Monitor the logger interface.

The Delay before locking period determines the time before users are locked out of the command interface. When this time expires, the user will need to re-enter the password.

2. Settings Changes (Command Language)

The below commands in dEX are equivalent to those mentioned in the previous section and should be put within a jobs code so that they are reinstated if the power to the logger is cycled:

PROFILE FTP_SERVER ALLOW_ANONYMOUS=NO

PROFILE FTP_SERVER USER=DATATAKER

PROFILE FTP_SERVER PASSWORD=NEWPASSWORD

P14=120   ‘delay before locking

PASSWORD=”MYPASSWORD”

NOTE: The above commands.

3. Limit Access to the ‘Monitor the Logger’ Interface

The monitor the logger interface is configured from the Customize dEX menu on the datalogger home page.

3.1 Hide Certain Diagnostic Features to Keep the FTP Password Safe

Enter the settings as shown for each of the menus. These options will remove some parts of the web interface where a user might be able to view profile settings and see the FTP password.

The local documents link will not work because we have removed the FTP anonymous user, so it should be removed too.

Save the changes by clicking Save Settings.

3.2 Prevent Editing of Mimics

After you have added all of the mimics you wish to use in the web interface, you will want to prevent users from changing them. To do this, you will need to re-enter the Customize dEX menu and uncheck the box next to Allow changes to mimics in the Security page.

Save the changes by clicking Save Settings.

4. Hiding the ‘Logger Home’ Menu Items

Now that all of the settings have been saved, you will want to hide the Customize dEX menu. To do this, open Windows Explorer and log into your dataTaker’s FTP server. Use the IP address of your logger, user name and password you created in the profile earlier.

Once logged in, open the WWW folder and rename the folder ‘needa’ to anything else (eg. needa1234). Next time the logger home screen is shown, the Customize dEX menu will not be shown and will not be accessible (it may be necessary to clear the browser cache for this page to reload correctly). It is also possible to hide the Configure the logger menu item using the same process but renaming the folder “jango” instead of “needa”.

The post Securing the dataTaker DT80 Web Services appeared first on CAS Dataloggers.