Problem reading right voltage values (PCI-6025E)

[MSoni]

PCI-6025E Analog Input reads maximum values of 10V for Ch9 to Ch16 and reads 0V for Ch1 to Ch8

And this happens when PCI-6025E, PCI-6024E and PCI-6602 3 PCI cards are installed

Another observation is when the PCI-6024E is taken out the readings on PCI-6025E are improved reading 0V for Ch1 to Ch16. How consistent it is, not sure. But yes the requirement is to use all 3 cards together.

[ZYOng]

What type of signals did you provide to the channel?

Note that NI does not specify what voltage a device will read when there is no signal connected. Reference: Incorrect Readings on Unconnected or Open Channels of DAQ Device

[MSoni]

The 3 PCI cards including the PCI-6025E was running LIVE on a system from many days acquiring various Analog Input signals in 0-10V range and converting to engineering values. The signals include +5VDC, +12VDC, +24VDC, Drive Speed, Speed Sensor, Input Speed, Output Speed in RPM, Pressure in PSI, Torque in lb/ft, so various sensor signals and using all 16 Analog Input channels along with Analog Output, Counter Output and Digital Output channels.

Suddenly the Analog Input readings began to malfunction, while debugging found channels 8-15 returns 9.995117V, regardless of actual input. And it was NOT consistent. Sometimes it returns back to normal 0V and sometimes goes back to 9.99V resulting in incorrect engineering values.

To debug further we disconnected the computer from the LIVE system and brought it to LAB for testing.

We wired the PCI-6025E to SCB-100 accessory to simulate the actual scenario and provided a zero voltage signal across the + and - terminals of the channel. We did this by shorting the Pin#1 AI GND and Pin#4 AI 8. And found we are reading -10V incorrectly instead of 0V. At the same time all other channels like AI 9 - AI15 reads 10V which is a problem also, whereas AI 0 - AI 7 are good reading 0-500mV.

When we short Pin#1 GND and Pin#6 AI 9, same problem.

So the same problem happens for Channels AI 8 to AI 15

Whereas, the Channels AI 0 to AI 7, reads 0 correctly when shorted.