DATAQ Instruments Application Notes and News

Dual-Channel Wireless Temperature Data Loggers

DATAQ Instruments is pleased to introduce the EL-WIFI-DTC and EL-WIFI-DTP+. These dual-channel wireless (802.11b compliant) temperature data loggers are capable of buffering over 1,000,000 temperature readings and transmitting that data to a PC via a WiFi router.

dual-channel temperature data loggers

The EL-WIFI-DTC can acquire temperature from -270 to 1300°C (-454 to 2372°F) using J, K, N or T-type thermocouples. Two 1.5 meter K-type thermocouple probes are included.

The EL-WIFI-DTP+ can acquire temperature from -40 to 125°C (-40 to 257°F), with an accuracy of ±0.2°C, using thermistor probes. Two 3 meter thermistor probes are included with the logger.

Both loggers include downloadable EasyLog WiFi Sensor software, allowing you to configure alarms, choose a temperature scale (C or F) and set sample & transmit intervals.

dual-channel temperature data loggers

In addition to setup and configuration, EasyLog WiFi Sensor software allows you to view and analyze  recorded data using a built in graph utility, and save that data in Microsoft Excel format with a single mouse click.

dual-channel temperature data loggers

Additional Reading:

Using Intelligent Oversampling to Extract Important Information

Oversampling is a feature whereby a data acquisition instrument can sample data at a faster rate than what is being reported in the software. Intelligent Oversampling allows the instrument to evaluate the data that isn’t being reported, and yield just the information you’re looking for (average, maximum, minimum, the DC equivalent or frequency, for example).

Our latest YouTube playlist demonstrates how intelligent oversampling works, and shows you how it is used in conjunction with WinDaq data acquisition software to derive average, minimum, maximum, RMS and Frequency data.

Read More On Intelligent Oversampling:

Intelligent Oversampling Enhances Data Acquisition

Intelligent Oversampling Methods Add Measurement Flexibility

 

Starter Kit Helps Win Science Fair Competition

DATAQ Instruments makes data acquisition hardware and software donations from time to time to young people who demonstrate the need for a particular measurement that we can satisfy. Examples are measurements in school projects, science fairs, and even Ph.D theses. We recently learned that two high school students used WinDaq high-speed software that we donated with one of our data acquisition starter kits to win a regional competition. In the words of their sponsor:

Three years ago your company sponsored our science fair project by supplying a software upgrade allowing high speed data acquisition.   Thank You.

science fair 2It took longer than I expected but the project was completed and entered into the 2015 Central Sound Regional Science Fair in Washington State.  The project won the Power and Transpiration Division and was one of seven finalists to compete for two spots to present at the National Science Fair in PA.  They also won the award for using metric units.

The project used a Proney Brake to measure the power curve of a wind turbine blade set.   The DAQ measured two linear hall effect sensor voltage that measured shaft torque and rotor speed.  From this they calculated wind turbine power as a function of rotor speed.

Enclosed is a picture of the students.  From left to right is Kyle and Kevin, both in 10 grade. Again Thank you and thanks for supporting the science fair community.

Our thanks to Kyle and Kevin for choosing DATAQ Instruments products for their project, and our heartiest congratulations for using them with such success.

EL-USB Battery Issues

We’ve noticed an uptick in the number of customers reporting that the batteries included with their EL-USB series data loggers are ‘dead on arrival’.

The battery included with most EL-USB series loggers is a 3.6V (½AA cell) lithium metal battery.

EL-USB Battery Issues

The problem can occur when a battery is unused for extended periods of time, like during extended transit times from the manufacturer to the end user for a new battery, or left unused at a customer site. In this situation, Lithium batteries can form a non-conductive internal layer; also known as a “passivation” layer.  This is technically a feature of the battery that prevents self-discharge, allowing for longer shelf life. An unfortunate side effect, is a drop in voltage when the battery is initially placed in your EL-USB series logger. The voltage drop can easily be mistaken for a dead battery.

You can remove the passivation layer in one of two ways. The first is to place the battery in your EL-USB series data logger and leave the logger connected to a PC for approximately 30 seconds. After 30 seconds has passed, remove and re-install the battery, resetting the data logger. The overall battery life is not affected.

A second, more immediate method is to momentarily short the battery, positive to negative. This can be done using a wire, or even a paper clip. It only takes a second to clear the passivation layer.

EL-USB Battery Issues

Sub-zero Thermocouple Measurements

Sub-zero thermocouple measurements

Figure 1 — Model DI-245 measurement ranges by thermocouple type.

“One of the best kept secrets in the instrumentation world is that sub-zero thermocouple measurements require thermocouples that are specially qualified for that application.”

Looking at the specs of a typical thermocouple data acquisition system might be a little misleading when it comes to interpreting temperature measurement capability. For example Figure 1 is a snap-shot of the thermocouple  measurement range for our model DI-245 voltage, mV, and thermocouple data acquisition system taken directly from the product’s data sheet. If you believe that measurements of sub-zero temperatures can be accomplished using almost any thermocouple type as implied by the table, you can be forgiven. One of the best kept secrets in the instrumentation world is that sub-zero thermocouple measurements require thermocouples that are specially qualified for that application.

The Sub-zero Thermocouple Measurement Problem

By “sub-zero” I mean any temperature measurement that is less 0 °C. It is generally not possible for thermocouple manufacturers to provide alloys that operate both above and below zero in the same thermocouple wire. And since the vast majority of thermocouple applications are for measurements above zero, that’s where the bulk of thermocouples are guaranteed to operate. Thermocouples for the substantially fewer sub-zero applications must be ordered specifically for that purpose. So, although instruments are designed to make the sub-zero measurements the weak link is the thermocouple itself, especially if it has not been specifically designed for such use. Unfortunately, the danger is that an unqualified thermocouple gives the appearance of working below zero but is actually generating large measurement errors. Likewise, a thermocouple that is qualified for sub-zero work may generate large errors above zero. So, if you make measurements both above and below zero, be sure to have a procedure in place that identifies one thermocouple qualification from the other.

Thermocouple Types for Sub-zero Work

Should you need to perform sub-zero work, generally certified type E and T thermocouples are used in that application. Other thermocouple types exhibit poor characteristics, like becoming brittle, succumbing to corrosion, or generating an exceedingly low EMF at cryogenic temperatures. 

Any reputable thermocouple supplier should be able to provide pricing and availability for thermocouples that are certified for sub-zero work If that’s what you need, be sure to convey so at the time of your order to ensure accurate measurements using our products or anyone else’s.

Additional Reading:

How To Power Multiple 4-20 mA Sensors

We’re often asked how to power multiple 4-20 mA sensors using a single power supply. While it is possible to do this, the usual cautions apply regarding ground loops and other subtleties. Readers who are new to measurements using sensors with 4-20 mA process current outputs should refer to our earlier article that explains basic concepts and configurations.

Multiple 4-20 mA Sensors, One Power Supply

So, you have multiple 2-wire sensors with 4-20 mA outputs and only one power supply. How can you make this work? Use this step-by-step process:

  1. Take an inventory of the minimum and maximum power supply requirements for each sensor. Choose the highest of the minimum and lowest of the maximum values of all sensors. Then pick a power supply voltage that is roughly half way between these two figures. For example, if the highest of the minimum power supply voltage for five sensors  is 10 V, and lowest of the maximum power supply voltage is 20 V, pick a power supply voltage of about 15 V. The actual value isn’t critical provided that you give yourself breathing room of a couple of volts or so from the two extremes.
  2. Multiply the number of 4-20 mA sensors to be powered by 0.02 and add 20%. This is the maximum current that the power supply is required to deliver in amperes. Again for five sensors, this value is 5 × 0.02 × 1.2 = .12 Adc, or 120 mA.
  3. Unless the instrument used to make the measurement has built-in shunts, you’ll need to add these externally. There are correct and incorrect placements depending upon the instrument, so refer to our earlier article here for complete information.
  4. Connect your sensors, power supply, and shunts (if required) as shown in Figure 1, where:
    • “E” represents the power supply
    • “R” is the shunt resistor. Replace “R” with an open circuit if the instrument has built-in shunt resistors.
    • “V” is the signal connected to the instrument.

That’s all there is to it. Using these guidelines there is no practical limit to the number of 4-20 mA sensors that can be powered by a single power supply, saving space and money.

Schematic of two or more 2-wire 4-20 mA sensors powered by a single power supply.

Figure 1 — Schematic of two or more 2-wire 4-20 mA sensors powered by a single power supply. (click to enlarge)

Active USB Extension Cables Limit Data Loss

Perhaps you have an application that requires your USB-connected data acquisition system to be positioned further from the PC than the 2 to 5 meter maximum USB cable length specification. The USB Active extension cable allows you to position your USB-connected data logger up to 15 meters (almost 50 feet) from the PC.

Active USB Extension Cable

As signals travels through a USB cable, they gradually lose strength, or attenuate. The further the signal travels, the weaker it gets. The end result is data loss. The USB Active extension cable prevents data loss by buffering data entering and exiting the cable. With data transfer rates up to 480 Mbps and no external power required the Active USB extension cable supports both high speed and low speed devices.

Active USB Extension Cable

Using a DATAQ Instruments DI-155 data acquisition starter kit, connected via a 10-meter (almost 33 feet) USB Active extension cable, we were able to record data at sample rates up to 10 kHz, gap free.

Changes to the Built-in Temperature Alert Server

There have been some changes to the server, built into the Temperature Alert TM-WIFI350 LAN-based temperature and humidity data logger. In the past, when typing the IP address of your TM-WIFI logger into a web browser, you were directed to ‘Developer Mode’. In Developer Mode you can set alarms, change connection parameters and enter email notification information. Data is stored locally in developer mode.

Temperature Alert server mode

The most recent version of the Temperature Alert server now directs you to ‘Sensor Cloud Mode’, where you’ll be forced to create a free Temperature Alert cloud account. In Sensor Cloud Mode, data is stored to the Temperature Alert Sensor cloud, where it can be accessed from any PC with an Internet connection. As with Developer Mode, Sensor Cloud Mode allows you to set alarms, view real-time data and enter a single email address where alert notifications can be sent. For a fee, you can send alerts to multiple email addresses, and receive periodic reports.

To avoid having to create an account, click the ‘Switch To Developer Mode’ link, located in the lower right-hand corner of the screen.

Temperature Alert server mode

Additional Reading:

Flood Sensor for Temperature Alert

Additional Features for the Temperature Alert LAN-based Temperature and Humidity Data Logger

 

Flood Sensor for Temperature Alert

The AC-FLDRJ is a flood sensor designed for use with the Temperature Alert TM-WIFI-350 LAN-based temperature and humidity data logger. Measuring just 2.5” x 3.25” x 1”, simply lay the sensor on a flat surface to detect the presence of conductive, non-flammable liquids. Built-in feet on the bottom of the AC-FLDRJ keep the sensor contacts just above the monitored surface to prevent false alarms. A center mounting hole allows the sensor to be bolted in place, for permanent installations.

Temperature Alert Flood Sensor

When the surface is dry, the sensor sends a ‘No Flood’ signal to your TM-WIFI-350. When a liquid is detected, a ‘Flood’ signal is sent. The TM-WIFI-350’s built in server allows you to configure the instrument so that an email alert can be sent when a ‘Flood’ signal is received.

Temperature Alert Flood Sensor

A second email can be sent when the liquid recedes (the TM-WIFI350 detects a ‘No Flood’ signal once again).

The AC-FLDRJ is available with cable lengths of 15, 30 and 50 feet, and will work with legacy products, including TM-WIFI220s sold AFTER January 20th, 2012 (with the latest firmware) and the TM-WIFI-330.

Additional Reading:

An Overview of the Temperature Alert LAN-based Temperature and Humidity Data Logger

Temperature and Humidity Data Loggers

 

Trouble Communicating With Your Ethernet Connected DI-720 or DI-730 EN-B

On This Page

Symptoms

Cause

Resolution

Verify that you’re installing the latest version of WinDaq

Verify that your Network Interface Card (NIC) has a static IP address

Disable any wireless connections

Verify Windows Firewall settings

Run the DATAQ IP Manager as an administrator

Make sure that your Ethernet cables are not more than 100 meters in length

Verify that your Ethernet cables are connected correctly

Reset your Network Interface Card (NIC)

Applies To

 

Symptoms

Upon installing WinDaq and running the DATAQ IP Manager, no instruments are found.

Your Network Interface Card is not listed in the “Select Network Adaptor” window.

An “Error binding UDP port 1234” error message

 

Cause

Could be the result of one or more of the following:

You’re running an older software installation

Your Network Interface Card (NIC) does not have a static IP address

A wireless router is attempting to assign you NIC an IP address

The IP Manager is not listed as an exception in Windows Firewall settings

You’re not running the DATAQ IP Manager as an administrator

You’re using Ethernet cables that exceed 100 meters

The instruments is not connected properly

The Network Interface Card is hung up

 

Resolution

To resolve these issues follow the steps below.

 

Verify that you’re installing the latest version of WinDaq

You can download the latest version of WinDaq for your DI-720/730-ENB at:

http://www.dataq.com/support/upgrades/record/g1lev3en.html

 

Verify that your Network Interface Card (NIC) has a static IP address

As outlined in the Installation Guide, verify that your NIC (TCP/IPv4) has a static IP address.

Ethernet Connected

 

Disable any wireless connections

Make sure that any wireless connection are disabled (not just disconnected).

To do so, open the Windows Control Panel, choose ‘Network and Internet’ and select ‘Change Adaptor Settings’.

Ethernet Connected

Right-click on the Wi-Fi connection and choose ‘Disable’

Ethernet Connected

 

 

Verify Windows Firewall settings

Make sure that the DATAQ IP Manager is allowed through the Windows firewall, for both Private and Public networks.

Ethernet Connected

To do so, open the Windows Control Panel, choose ‘System and Security’ and select ‘Allow an app through Windows Firewall’.

Select both the ‘Private’ and ‘Public’ checkboxes.

 

Run the DATAQ IP Manager as an administrator

Right-click on the ‘IP Manager’ shortcut and choose ‘Run as administrator’

Ethernet Connected

Make sure that your Ethernet cables are not more than 100 meters in length

The Ethernet cable connecting your DI-720/730 EN-B to the PC and ones between synced units cannot exceed 100 meters in length.

Ethernet Connected

Verify that your Ethernet cables are connected correctly

The “Toward PC” connection on the back of the first synced (unsynced) DI-720/730 EN-B should be connected to the Ethernet port of the PC or network. The “Toward PC” connection of the second synced unit should be connected to the “Expansion” connection of the first synced unit, the “Toward PC” connection on the third synced unit to the “Expansion” connection on the second synced unit, etc.

Ethernet Connected

Reset your Network Interface Card (NIC)

To reset your Network Interface Card, open the Windows Control Panel, choose ‘Network and Internet’ and select ‘Change Adaptor Settings’.

Ethernet Connected

Right-click on the network connection and choose ‘Disable’

Ethernet Connected

With the connection disabled, right-click again and choose ‘Enable’

Ethernet Connected

Applies to

All DI-720, DI-722 and DI-730 EN instruments, the DI-785, DI-788 and the DI-5001-E