Circumvent 9233 IEPE

[derek@clustr.dev]

Is possible to block the IEPE from the 9233. I would like to aquire signals from accelerometers which have already gone through some buffering circuitry. I would use the 9215, but I want to take advantage of the 24-Bits and anti-alias filtering of the 9233. What are my options?

Thanks in advance.

[A.S.]

Hi Derek,
Here's is an excerpt from the cRIO-9233 manual below:
"The cRIO-9233 IEPE excitation current and AC coupling are always
enabled except when the module is in Transducer Electronic Data
Sheet (TEDS) mode."

So the only option you have is to use the TEDS mode which will disable the IEPE excitation. The cRIO-9211 is another viable option that has 24-bit resolution. However, it doesn't have the anti-aliasing filter built in, as the 9233.

Please let us know if you have any further questions.

A Saha
Applications Engineer
National Instruments

[A.S.]

Hi Derek,
A point of clarification: Although the cRIO-9211 can acquire 24-bit signals, its a thermocouple module that is limited to only 15 S/s. I assume that the accelerometer needs a much higher acquisition rate than that. Also, if you put the cRIO-9233 in TEDS mode, it infact reads digital data from the TEDS sensor, instead of reading analog data directly. So that would not be a viable option either. The closest option is to use the cRIO-9215 in the meantime, for development purposes.

[derek@clustr.dev]

Is it possible to use an external circuit prior to the 9233 to block the IEPE. (i.e. series capacitor)?

[preston_johnson]

It may not be necessary to put an external circuit in front of the 9233. For example, many sensors do not consume the 2ma of power, and thus by themselves block the 2ma of current from the IEPE. Further, the 24volt that is put on the analog inputs as part of the IEPE (24V, 2ma) is removed with the AC coupling feature of the 9233. The best way to determine how this will work for you is to connect it to the sensors and see what the results are.

[Jack_A.]

Derek -

A source follower amplifier will remove the IEPE from your signal if you are worried about the 2mA of current that your device would see if connected directly to the cRIO 9233. PCB has a handful of different types of in-line source followers.

Hope this helps.
-Jack

[Jack_A.]

To be more specific on my previous post, I have tested PCB's ICP source follower amplifier model# 401A04. Contact PCB for more details since it is not listed on their website.

-Jack

[slm]

How can I create a virtual TEDS file?

[slm]

A. S.

I guess my previous post is to you.  How do I create a virtual TEDS?

[slm]

A. Saha: Can you tell LabView to ignore the TEDS data response?  Otherwise this device is impossible to use with legacy microphones and other sensors.