9235 & cable length

[Sinha]

Dear All

I am planning to use 8xNI 9235 SG module in cDAQ-9172 chassis.

Can someone advice me

1. What is the max strain gauge cable length that can be supported. I have rough estimate that it can run upto around 100metres

2. If using with Signal Express 2.5 or 3.0, 1000samples/sec/channels would be achieveable

3. Whether the excitation voltage is software adjustable

Sinha

[DFGray · Accepted solution]

1. Longer cables lead to degraded signal gain.  The maximum length of your cables will depend on the cables themselves.  See page 13 of the 9245 manual for a discussion.  Note that longer cables are also more susceptible to noise.  Even if you can tolerate the gain loss, you may not be able to tolerate the noise.  This will depend on your cables, how well they are connected and shielded, and the amount of electrical noise in the area.
2. 64 channels at 1kHz each should be possible with SignalExpress 2.5 or 3.0.  Version 3.0 should work better, since it had some large channel count enhancements over 2.5 (and we continued to improve for 3.5!).
3. The excitation is a constant value (2.0V ± 1%).  It cannot be changed. See page 28 of the manual for excitation specifications.