ADC Channel crosstalk in xPC

Question

Perry 2014-7-16

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/142156-adc-channel-crosstalk-in-xpc

Problem Description:

xPC and Matlab (2013b) Board - Measurement Computing PCI-DAS-1002

The data acquisition card, in single ended mode, is connected only as follows

Ch2 (Pin 5) = 5V from card (Pin 48) Ch 9 (Pin 6) = connected via a 25k resistor to the 5V (Pin 48)

Everything else is completely disconnected.

With this setup, the measurement from xPC software for Ch2 and 9 are similar (near 5V) although Ch 9 is a bit lower (by ~0.03V) and bounces around more than . DMM measurement shows that CH9 pin is slightly lower than Ch2 pin (by around 0.01V) when measured with respect to ground.

However, when another channel, e.g. Ch1 on Pin 4 is grounded, then Ch9 reading, as read from software will drop to 3.88V. Ch 2 reading remains near 5V. DMM measurement of the voltage of Ch9 pin and ground is still 4.98V ish and measurement of Ch2 pin is steady at 5V (or 4.99V). Ch1 is read correctly as 0V.

Conclusion: The channel with the 25kOhm output resistance is significantly affected by the other channels' voltages (e.g. Ch 1).

Is this issue the same as here: http://www.mathworks.com/matlabcentral/answers/92795-why-does-my-a-d-board-experience-crosstalk-between-channels-when-using-xpc-target-r14sp2

Note that Measurement Computing's own software (InstaCAL) does not have this problem so it seems to be a driver issue. Does Mathworks have a solution (updated driver to use)?

Thanks Perry