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Help with NI PXI 4070 DMM and NI PXI MUX 2501

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Dear Alls,

 

So sorry to post a simple question, but I could not figure it out.

My PXI1033 chasis has NI PXI 4070 DMM and NI PXI MUX 2501, terminal block NI-TB2605, configured as One-wire mode by MAX.

I try to measure 3 voltages (from 2V to 5V) by connecting them to ch0, ch1, ch2 of MUX2501 (e.g screw terminal 67,66,65 and common screw terminal 27).

All device pass self-test at MAX.

I then use NI-DMM/Switch Express, switch devices added and also scan list.

Trigger is PXI trigger; Handshaking (PXI trigger 0 and PXI trigger 1)

However, I could not measure any signals.

I also try with some other example in LabVIEW help, but still have no result.

Am I missing something?

And, although the trigger section is very clear explained, I have no idea how the DMM conduct its measurement through multiplexer switch. How did DMM connect to MUX?

I noticed that the DMM and the switch share the same trigger bus (both of them has trigger bus 1), but their local buses are different (DMM: local buses left/right = 2,4 and MUX local buses left/right = 3,5)

Your advices are highly appreciated.

Thank you.

Van.

 

 

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Sorry, I found an help from NI website

It seems that I missed the cable connecting from MUX front to DMM input, as shown in attached file.

It it's correct, please advise me what it the name of that cable?

Thank you.

Van.

 

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thanhvan

Way to go! You exactly need that cable!
Goodluck!

Lonestar

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Accepted by topic author thanhvan

Thanks Lonestar!

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Hey Thanhvan,

 

The cable is an easy way to connect the 2501 to the DMM, but it is not required.  You can definitely connect DMM leads directly to the pins and measure the correct values without the BAN4 cable.  In the 1-wire 48x1 topology, the common channel is COM0+ (pin 61), not COM0- (27).  Apologies if the pinout isn't clear; we'll clarify that.

 

Connect the DMM+ to pin 61 and that should do the trick.  Note that in the 1-wire mode, all the return paths need to be wired together and then connected directly to DMM-.  If you want to isolate each return lead, then you'll need to use a 2-wire mode.

-John Sullivan
Problem Solver
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Hi John,

 

Thanks for the instruction.

The common channel is written in NI help, pin 27 (COM0-), so it is important to have an update.

Van.

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