DATAQ Instruments Application Notes and News

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

Die Cushion Qualification

DATAQ Instruments was recently mentioned in Evaluation Engineering magazine‘s special report on data acquisition systems. The feature focused on applications in machine condition monitoring, which is an area that is very popular for users of our equipment. So, we thought we’d publish an overview of it here for our readers. The specific application was monitoring the condition of a die cushion.

What’s a Die Cushion?

As its name implies, a die cushion is a device attached to a metal press to absorb and distribute the force of the process. This activity serves to ensure a more uniform pressure over the die blank and throughout the press’s stroke. When properly configured, a die cushion enhances yield, quality, and repeatability of produced parts.

Figure 1 -- The Advanced CODAS integration utility is only of many analysis functions that may be applied to WinDaq-acquire data.

Figure 1 — The Advanced CODAS integration utility is only one of many analysis functions that may be applied to WinDaq-acquired data. Each is an easy-to-use, non-programming point-and-click utility.

Die Cushion Measurements

Our customer is a press manufacturer, and wanted to qualify the function of a die cushion in a particular application. The die cushion was a hydraulic device, so a pressure sensor with a 4-20 mA output was fitted to it and connected to a DI-718B-U data acquisition system running WinDaq data acquisition software. Conditioning and excitation for the sensor was provided by a DI-8B42-01 amplifier, that was installed inside the DI-718b instrument, resulting in a compact and powerful data acquisition solution.

Figure 2 -- Screen shot of acquired pressure waveform (top), and other two analysis waveforms generated by Advanced CODAS analysis software.

Figure 2 — Screen shot of acquired pressure waveform (top), and other two calculated waveforms generated by Advanced CODAS analysis software: Integrated and differentiated pressure (middle and bottom respectively.) Diamonds show the peak values of each, which are used to characterize die cushion performance.

Only one measurement was acquired by the instrument, but a pressure curve by itself was not enough to qualify die cushion condition. To gain the necessary insights, post processing was required and supplied by DATAQ Instruments’ Advanced CODAS waveform analysis software. That package allowed meaningful post-acquisition analysis by generating two calculated channels derived from the original pressure waveform: its integral and derivative.

Integrated Die Cushion Pressure

The original die cushion pressure waveform was passed through Advanced CODAS’s integration utility to produce an output that was aligned in time with the pressure signal, but could be interpreted as the amount of work done by the die cushion. It is extremely difficult to glean die cushion work from the pressure waveform alone. Variations in the pressure waveform from press cycle to press cycle, and from part to part can be extreme. However, integrating the pressure waveform accounts for all of these variations by producing a result equal to the area bounded by the curve of the pressure signal with associated engineering units of psi-seconds. This terminal value of the integral before reset can be viewed as the total amount of work done by the die cushion for the press cycle. It follows that a die cushion that has failed in some manner that affects the pressure signal will also affect the total work done by the die cushion over the press cycle. If the die cushion develops a leak, overall pressure will decrease, which will immediately impact total work done by the cushion resulting in a lower terminal value.

compressed die cushion

Figure 3 — A compressed view of acquired and calculated data showing multiple press cycles, and demonstrating the running calculation capability of Advanced CODAS analysis software.

The utility of the integrator facility provided by Advanced CODAS is enhanced by the multiple reset methods that can be configured. In this situation, pressure always returned to zero after a press cycle, so the integrator was configured to reset upon zero crossing of the pressure waveform, which ensured automatic and meaningful measurements per press cycle.

Differentiated Die Cushion Pressure

The total amount of work done by the die cushion is only half of the story. Also of great interest is the stress applied to the device during press cycles. This quantity is revealed by another Advanced CODAS utility that differentiates the pressure waveform with respect to time. Scaled in units of psi/second, this result quantifies the abuse absorbed by the die cushion, caused mostly by large, initially applied pressures. Since derivatives tend to produce noisy results, Advanced CODAS allows derivatives to be calculated over adjustable window sizes. The derivative of the pressure waveform discussed here responded well to a window size of 7.

Putting It All Together

Figure 1 shows the Advanced CODAS configuration application where various calculation functions and options are selected and applied to acquired data. It features a point-and-click, non-programming user interface for ease of use. Shown is the Integration screen with all of its reset methods.

Figure 2 is a screen capture of only one cycle of the analysis result. The top-most waveform is acquired die cushion pressure in units of psi. The middle waveform is the integral of pressure, reset upon zero-crossing of the pressure waveform. Its units are psi-seconds, and the total amount of work performed for this single press cycle is the peak value shown in the diamond, about 620 psi-sec. The bottom waveform of Figure 2 is the derivative of pressure. In units of psi/second, the peak value of approximately 104,000 psi/sec is shown in the diamond and represents the most extreme stress experienced by the die cushion in that particular cycle.

It is important to note that Advanced CODAS is a waveform analysis package that produces a running calculation. Figure 3 is a more compressed view of the analysis showing that calculations are applied automatically across multiple press cycles.

Additional Reading:

Advanced CODAS Analysis Software

DI-718B Data Acquisition Systems

DI-8B42-01 4-20 mA Transmitter Amplifier

All DI-8B amplifiers

 

Same Great Content with a New Look

We are proud to announce a top-to-bottom redesign of www.dataq.com. This effort draws upon your comments over the years to yield a new look and feel while providing easier access to information.

DATAQ Instruments, Inc. New Home Page

DATAQ Instruments, Inc. New Home Page

Among other improvements you’ll find a new Products menu that puts you only a few mouse hovers away from a range of product solutions for most applications. We’ve laced the website with product filter pages that allow you to easily determine product options for specific requirements. And all product pages have a clean, easy-to-use design that describe the product, its price, available options, and similar alternative solutions.

Please take some time to explore the new website that you helped to deign, and feel free to let us know your thoughts in the comment section.

 

WinDaq/XL Real-time Bridging Software

WinDaq/XL is real-time bridging software that allows users to stream data from WinDaq data acquisition software or the WinDaq Waveform Browser, into a Microsoft Excel spreadsheet. Once there, users can take full advantage of Excels exceptional ability to perform calculations and chart data.

Since it’s initial release several years ago, features have been added to WinDaq/XL, and the data storage capacity of Microsoft Excel has expanded from 65,536 rows, to well over a million.

A ‘High Speed’ option in WinDaq/XL now allows data to be buffered for high speed data acquisition, and the time/date stamp is fully customizable.

WinDaq/XL Real-time Bridging Software

See our multimedia presentation demonstrating the power of the WinDaq/XL add-on!

 

Additional Reading:

WinDaq Data Acquisition Software-to-Excel Real Time Link

Getting Started With WinDaq/XL

WiFi Range Considerations

We carry several WiFi products and we’re often asked about their range. In other words, how far from the WiFi router can the data loggers be located? Unfortunately, this is like asking us to forecast the weather next Sunday. There are simply too many variables for us to predict how well any WiFi product will operate in all but the most clear cut cases. Beyond the distance between the data logger and the WiFi router, WiFi range is affected by the number of walls and floors that separate them, their construction, ambient levels of electromagnetic activity, electrical wiring density, and more.

None of this helps you arrive at an answer for the range question, but here are some ideas that may.

WiFi Range Audit

Why not discover the answer to the WiFi range question empirically? Given the proliferation of  WiFi-enabled portable devices (most notably cell phones and tablet computers), try syncing such a device to your WiFi network, place it where you want to locate the WiFi data logger, and see how well it performs. Try downloading a large file to get a feel for the fidelity of the WiFi signal in your area of interest. If the download goes well, you have every reason to believe that a WiFi data logger will work equally well.

The Unintentional WiFi Faraday Cage

A Faraday cage is a metallic enclosure that impedes or inhibits electromagnetic energy. Radio devices placed inside such a cage occupy an RF dead zone. Unfortunately, many environments  where customers need to make measurements are unintentional Faraday cages. I’m thinking of ovens, refrigerators, and  freezers that are usually if not always constructed with a grounded metallic shell. Placing a WiFi product inside such an area may isolate it from the outside RF world. Again, use the WiFi Range audit suggestion above to predict performance in this situation. Start a large download, and then place the device inside the environment and close the door.

External WiFi Data Loggers

When an environment that you’d like to measure presents a Faraday cage-like dilemma, consider a probe-type data logger where the probe is placed in the monitored environment while the WiFi data logger remains outside. Many ovens, refrigerators, and freezers provide an instrument port for such a purpose, so you won’t have to drill holes in most cases.

Further reading:

EL-WiFi Series Data Loggers

TemperatureAlert Data Loggers

 

 

Why You Need Channel-to-channel Isolation

It’s difficult to temper excitement about DATAQ Instruments’ model DI-245 data acquisition system. Beyond thermocouple-based measurements and a superb voltage measurement range, there’s the instrument’s incredible isolation specification. We’ve given you a multimedia presentation and a related post that describes it (see here and here), but this post focuses on an often-overlooked nuance of isolated instruments.

Channel-to-channel Isolation

Trouble without channel-to-channel isolation.

DI-245 high common mode voltage application (click to enlarge.)

Many instruments offer input-to-output isolation and tout that as a great feature. Some isolation is better than none, but it’s important to understand exactly what you get with an instrument that offers only input-to-output isolation: All channels share a common ground that is isolated from power. There are no consequences to this if you connect only one channel to a multi-channel instrument. That single channel’s ground reference is free to float to any value within the isolation spec of the instrument without damage. However, connect a second channel at the same time and you could be headed for major problems.

A nearby graphic reproduces the test setup we used in our multimedia presentation where we deployed the DI-245 in a high common mode voltage situation. Can you imagine what would have occurred if the DI-245 supported only input-to-output and no channel-to-channel isolation? Right…instant fireworks. If it isn’t clear why, look closely at the relationship between channels one and two. Channel one has been driven off ground by a 340-V peak-to-peak signal (ordinary US line voltage), while channel two is grounded. If the DI-245 lacked channel-to-channel isolation, meaning all input channels share the same ground, connecting channel two in the manner shown shorts line voltage to ground. Ouch! Fortunately, we anticipated this problem and designed the DI-245 with both input-to-output and channel-to-channel isolation.

So, why would any manufacturer design a product with only input-to-output isolation (and there are many who do?) It simply costs less to provide only input-to-output isolation, which translates into a lower selling price while still allowing the company to advertise the product as having isolation. It’s a smokescreen laid in front of a bear trap for customers whose budgets match their instrumentation experience. With the DI-245 you can have it both ways: World-class isolation at a budget-friendly price.

 Additional Reading:

DI-245 mV, V, and Thermocouple Data Acquisition System

How To Calculate Common Mode Rejection Ratio

Common Mode Rejection Ratio Defined

Common mode rejection ratio doesn’t seem at all common. In fact, it sounds rather fancy and complicated. But it’s actually a simple concept. Recall that a common mode voltage is one that occurs simultaneously and in phase on both inputs of a differential amplifier. For a dramatic demonstration of this, please watch the video you’ll find at this link. Channel one’s applied signal in the video has two components:

  • A common mode voltage equal to 340-V peak-to-peak (standard US ac line voltage)
  • A normal mode voltage equal to the thermocouple signal.
Common mode and normal mode voltages

The relationship of common mode, normal mode, and output voltages when applied to a differential amplifier (click to enlarge.)

The nearby graphic helps to reinforce what’s actually going on in the demonstration. Line A in blue is a composite of the applied normal mode (thermocouple) and common mode (line voltage) signals that we applied to the (+) input of the DI-245’s channel 1. You can see that it doesn’t have a consistent amplitude, since it’s a sum of both the signal of interest (thermocouple) and the signal we’d like to reject (line voltage.) Line B in red is pure common mode signal without a normal mode component that’s applied to channel 1’s (-) input. You can see by studying these plots that the common mode component is applied simultaneously and in phase with both amplifier inputs. That prerequisite being met, the differential amplifier can do its job to produce an output that’s the difference between the signals applied to its inputs. The result is shown in green as line C. Of course, the relative signal amplitudes depicted in the plot are way out of proportion for clarity and to avoid complicating the issue with logarithmic scales. The common mode signal is hundreds of volts in the demonstration while the normal model signal is milli-volts with only micro-volt changes.

 Common Mode Rejection Ratio Calculation

Now that you understand what signal components are involved and how they relate, it’s time to actually calculate a measure of the amplifier’s ability to reject common mode signals and pass the normal mode signal of interest. The term common mode rejection ratio defines this measure and it’s the ratio of output-to-input signal magnitude. Turning back to the demonstration, we applied a 340-V peak-to-peak common mode signal. Since it’s ac in the shape of a sine wave at 60 Hz we should convert it to its dc equivalent for calculation purposes and use the value 120 Vrms. From the video the narrator noted that the signal on channel one moved the equivalent of about 9 micro-volts with the common mode signal applied. This implies a common mode rejection ratio value of: The above means that for every volt of common mode voltage we apply to a DI-245 input channel, the output will change by only 75 nV. Not bad for such an inexpensive solution as the DI-245! However, it’s kind of clumsy to refer to common mode rejection using scientific notation, so we commonly convert it into a logarithmic value in decibels (dB): equation2 So, in this demonstration the DI-245 may be described as providing about -142 dB of common mode rejection, meaning that the common mode voltage was reduced by 142 dB.

 A Word of Caution

Before you apply the demonstration and calculations referenced in this post, be sure that your instrument will tolerate a common mode line voltage. Most won’t and those that fail will do so spectacularly.

More reading:

Model DI-245 Thermocouple, Voltage, Millivolt Data Acquisition System

A Graphic Common Mode Voltage Demonstration

The Ability of the DI-245 to Reject Common Mode Voltage

The ability of the DI-245 to reject common mode voltage is unmatched in the $75 per channel price range.

To demonstrate the ability of the DI-245 to reject common mode (error) voltage, we connected K-type thermocouples to channels 1 and 2. With the thermocouple on channel 2 grounded, we then connected line voltage directly to the thermocouple on channel 1. This allowed us to demonstrate not only the common mode rejection, but also the channel-to-channel crosstalk rejection of the DI-245.

The ability of the DI-245 to reject common mode voltage As the following video illustrates, the results were impressive, to say the least!

Additional Reading:

How to Eliminate Noise in Data Logging and Data Acquisition Measurements Introducing the DI-245 Thermocouple and Voltage Data Acquisition System

EL-WIFI-Alert Alarm Indicator

The stand-alone EL-WIFI-Alert alarm indicator is an add-on for EL-WIFI series temperature and humidity data loggers. The EL-WIFI-Alert produces an audible and visual alert when an alarm level on one of your EL-WIFI temperature and humidity data loggers (installed on the same wireless network) is breached.

EL-WIFI-Alert alarm indicator

Multiple EL-WIFI-Alert units can be placed in remote locations, out of sight of the EL-WIFI loggers themselves and your PC, alerting users to alarms that might otherwise get overlooked. With 10 volume settings, 9 alarm sounds and bright, flashing LEDs, the EL-WIFI-Alert is a great compliment to the alerts already visible on your EL-WIFI logger and in the WIFI Sensor Software.

 

Additional Reading:

Configuring the All-new EL-WIFI-TH Using EasyLog WiFi Software

Cloud-based Device Management for EL-WIFI Data Loggers