why does SC-2345 / E Series board have DGND tied to Chassis GND?

[icebear]

Grounding isolation problems with SC-2345 chassis.

In checking the SC-2345 carrier, even with no modules installed, I find that DGND (pin 44 for example) is tied to chassis ground on the computer as soon as the card is connected.  I am connecting directly from the terminal strip on the chassis.  These should be isolated, from all the posts and manuals that I have read.  This problem appears to be true with both the PWR-01 and PWR-02 options.  It does appear AI sense may be isolated, but noise on our digital lines has been resulting in test failures.  How can I isolate my digital signals and specifically my signal ground for encoders using this hardware?  This appears to be true with both an E series PCI-16XE and M series PCI-6251 card. 

Thanks in advance for any insights.

[Abhinav T]

Hi,

None of the DAQ cards you are using are isolated. The 2345's Digital Ground pin is directly connected to the PCI DAQ card - and the digital grounds on each of those is tied to chassis ground.

Can you point me to the resources you found that suggested otherwise?

Thanks!