PXI-2503 SFP not showing correct COM"X" number?

[janaf]

Hi,

I have some PXI-2503 that I am using for the first time. Using it in 2-wire 24x1 mode

1) It seems to me like the SFP is always showing "COM0" whichever channel is used. My understanding is that it should be routing signals via COM0 for chan 0-5, COM1 for chan 6-11 COM2 for chan 12-17 etc and measurements show that too. But in the SFP it always indicates routing via COM0?

2) Question; is the pinout number of the TB2605 screw terminals, the asme as the numbers for the pinout of the PXI-2503? It seem to be so. Can someone confirm?

Thanks 

[Davidek · Accepted solution]

Hi janaf

1. Using the 2-wire 24x1 topology you are multiplexing 24 inputs to a single line. So you should only have one Common port. I guess the schematic on page 3 in the PXI-2503 Specifications has you confused. Please note the BC01, BC02 and BC03 relays in the schematic. If you switch to the Relays tab in the Soft Front Panel you will see that they are all closed in the mode your are using, meaning that signals from all inputs can reach com0.

If you change the topology to "2-Wire Dual 12x1 MUX" you will notice that bc02 turns open and in the Schematic tab you will now have an option to change bank in the top right corner. In this case Bank 0 uses com0 and Bank 1 uses com2

2. Please see this document, the pinout changes with topology

Best Regards

David

NISW

[janaf]

Thanks David for the pinout doc.

I read somewhere that input 0-5 are always via COM0, input 6-11 via COM1 etc. So I measured and it seems that it may be so, but with 2-wire 24x1 topology, COM0+, COM1+, COM2+ etc are all interconnected.