SH68-68-EPM vs

[Foreshadow20]

Hi,

I noticed on a few schematics of our systems that the cables used for the PXI-6255 and PXI-6225 are different per channel.

Connector 0 has SH68-68-EPM

Connector 1 has SHC68-68

Shouldn't both be the same?

What is the proper cable that should be used?

What is the effect if we change cables?

Note that on some programs they do some insane software multiplication on mV signals (bad hardware designs). For example, a 30mV signal that is multiplied by 80.

Thanks

[niarena]

I guess the answer is on this datasheet, the SHC68-68 does not have shields between the analog and digital signals, the EPM has improved noise rejection. 

Shielded Cables for 68-Pin Devices - http://sine.ni.com/nips/cds/view/p/lang/en/nid/11785

The EPM Series, feature separate digital and analog sections, a double-grounded shield, individually shielded analog outputs, individually shielded twisted pairs for all analog input, and twisted pairs for critical digital I/O.

Also, check these for the connection:

Dimensional Drawing for SHC68-68

http://digital.ni.com/hardref.nsf/websearch/b22138a8428635d08625806f00780f5a

Dimensional Drawing for SHC68-68-EPM

http://digital.ni.com/hardref.nsf/websearch/e52b7a9381e03cae86257361004959aa

http://digital.ni.com/public.nsf/allkb/DE2D842E545DE64B86256F78006EAB1A

[Foreshadow20]

Thanks niarena.

Apparently when we originally bought the system from NI, we requested a plug-and-play system with all the cards and cables, which they selected those cables for the card.

Would it be suggested to swap all SHC68-68 for the SHC68-68-EPM cables?

[niarena]

It depends on the sensitivity of the circuit, it the signals do not need them, then, not, it is just a matter of how it was designed