Can I connect my PXI modules to the SCXI switches through the backplane/bus of my Chassis?

[sm07]

I have a PXI 1050 Chassis with two SCXI-1129 modules with an SCXI-1334 accessory attached to each. I also have PXI modules such as PXI-5401 (Function Gen.), PXI-6704 (Analogue Output), and PXI-4072 and 4060 (DMMs). I would like to be able output my analog signal (and Func Gen) through the 1334 module to the outside world, but I am not sure how to do this. For example, I would like to connect the 5401 output line to r0c0 of the switch matrix through the chassis' bus, and then when i close the r0c0 relay, my signal will be sent out out.
I will eventually have another device which i will attach to the 1334 along r0 (i.e. r0c16) which this signal will be driving.
Also, I would like to know how to do this with an input, i.e. read an analog signal coming into the 1334 using the DMM.

How would i go about doing this?

any help would be GREATLY appreciated

[chericks1]

Hi sm07,

To verify, you want to connect the signal generated from the PXI-5401 to the High-Voltage Analog Bus (HVAB).  You also want to connect the signal coming out of the HVAB to either the PXI-4060 or PXI-4072.  Is this correct?

In theory it is possible.  There are two analog bus lines AB0+/- and AB2+/- that are available on the HVAB.  One of these could carry your 2-wire PXI-5401 generated signal and the other could carry your 2-wire voltage signal you want to measure with a DMM.  Interfacing (connecting) to the HVAB is where you're going to run into problems. 

Typically, customers use the HVAB to carry analog signals from a switch to a DMM.  The HV8-BAN4 cable, NI P/N: 185444-0x (x = 1, 2, or R18, depending on length) was created to keep connectivity simple.  The HV8-BAN4 cable connects AB0+ to HI, AB0- to LO, AB2+ to HI SENSE and AB2- to LO SENSE so that any DMM measurements up to 4-wire resistance is a piece of cake (easy).  I've attached a picture of the SCXI-1129 in its 2-Wire 4x64 Matrix Topology so you can visualize how AB0+/- and AB2+/- would be connected to R0+/- and R2+/-, respectively. 

To not use this HV8-BAN4 cable makes connectivity not as simple.  Are you sure you don't want to use one?  Let's look at your application for a second.  If I was spec'ing out your system, I would use a HV8-BAN4 cable to connect one of the DMMs to the HVAB, and then connect the other DMM (if used) and the PXI-5401 to rows of the matrix (other than R0+/- and R2+/-, because those are the rows that could be connected to AB0+/- and AB2+/-).  

In short, you could connect the PXI-4072 to any switch using the HV8-BAN4 cable and the HVAB backplane (SCXI-135x), which would eventually connect the PXI-4072 to R0 and R2 of any SCXI-1129 switch module.  Then you could connect the PXI-4060 to R1+/- directly to a SCXI-1129 switch module via the SCXI-1334 terminal block, and could connect the PXI-5401 to R3+/- also via the SCXI-1334.  Done! Depending on your application, of course.

However, if you really want to connect the PXI-5401 via the HVAB, there are ways of getting it done.  One way would be to cut a HV8-BAN4 cable to access the AB0+/- and AB2+/- signals separately.  I've attached the HV8 Connector Pinout (I believe it is the cable's connector, not the cable's mating connector) and the BAN4 Signal Names and Wire Colors below if this is what you choose to do. 

If it helps in any way, the black connector on the rear of the SCXI-1129 that interfaces to the HVAB is a 2x5 Molex Mini-Fit(TM) 4.20mm BMI.   

Best of luck!

Chad Erickson

Switch Product Support Engineer

NI - USA