Switch Hardware and Software

Showing results for 
Search instead for 
Did you mean: 

Measure resistance by using PXI2503

Go to solution

Hi, I'm trying to understand how PXI-2503 measure resistance by 2 wires of 4*6 matrix.

and I did try several different setup on my board but I couldnt recieve correct value of resistor.



I'm using the example from LabView8.5 (niSwitch DMM Switch Synchronous Scanning.vi)

my scan list input (c0->r0) under switch

range is 10000 and resolution 100m under DMM



I did try several set up, 

1. I put a resistor between C0+,AB0+ and r0+,AB0- ; and c0-, r0- connect to GND,  (this setup gave me some graph but not resistance)

2. I put the resistor between c0+,r0+ and AB0+(they are connect) and c0-,r0-,AB0- (but this is not giving anything.


is my setup is wrong? why I could not recieve any resistance..

thank you for any helping




0 Kudos
Message 1 of 16

Hi Newer104,


I understand where you're putting the resistor.  Where are you putting the DMM connections?




Chad Erickson

Switch Product Support Engineer


0 Kudos
Message 2 of 16

Hi, Chad


I have a cable assy (type LV6-BAN4, 18CM) . I put it into the analog bus connectors which locate at the TB-2606.



0 Kudos
Message 3 of 16
Accepted by topic author Newer104

Hi Newer104,


The issue may be that the analog bus relay is not closed.  Refer to the following picture and note that the ab0 relays must be closed to create a path between the rows/columns and the analog bus.


2503 resistance.JPG 



If I understand correctly, then I recommend to place the resistor across c0+ and c0- and to create the following scan list entry:


r0->c0 & r0->ab0;


Let me know if this solves your problem.  Best regards!


Chad Erickson

Switch Product Support Engineer


Message 4 of 16

Hi, Chad


thanks for helping!


do you mean I only need to connect the resistor to c0+ and c0- ? and leave other(AB0+,AB-,r0-,r0+) open?


I did that and I got nothing on the graph.


then I got a very noise sound (not high fan sound) when I try to change the trigger input to Immediate in the switch. 



0 Kudos
Message 5 of 16

Hi Newer104,


I reread your first post and it states you placed the resistor between ab0+ and ab0-.  If you cannot read the resistance when the resistor is placed here, then I recommend to verify there is continuity (low resistance or short-circuit) from one end of the LV6 to BAN4 cable to the other. 


You can also perform this continuity test on the TB-2606 terminal block to verify low resistance between the front connector and screw terminal.  The pinout of the terminal block front connector is shown below.




Hope this helps!


Chad Erickson

Switch Product Support Engineer


0 Kudos
Message 6 of 16

Hi Chad,


I can read the value when resistor is only connect with AB0.  but not with c0 and r0.  here is the diagram for my setup. I hope it will be easy to understand.




Download All
0 Kudos
Message 7 of 16
Sorry, the resolution is 100m not 10.
0 Kudos
Message 8 of 16

Chad! I can read the resistance value already. I finally put the AB0+ and AB0- with c0+ and c0- connect to the resistor. and they gave me the right value.


Thanks for suggestion.

0 Kudos
Message 9 of 16

Hi Newer104,


I think we're getting close.  Because you can read the resistance when it is placed between ab0+ and ab0-, we know the connections between the DMM and switch are not the problem.  The next logical step is to troubleshoot the terminal block and switch module.


1. When you run the LabVIEW VI, do you hear the relays clicking?


To troubleshoot the terminal block, I recommend you use the NI-SWITCH Soft Front Panel to connect r0+ and c0+ and then measure the continuity between r0+ and c0+ (on the TB-2606 terminal block).


Switch Soft Front Panel

Start>>All Programs>>National Instruments>>NI-SWITCH>>NI-SWITCH Soft Front Panel


2. Can you measure continuity between r0+ and c0+ (on the TB-2606 terminal block) when they are connected in the NI-SWITCH Soft Front Panel? 


To troubleshoot the switch, I recommend that you place the resistor across r0+ and r0- and use the DMM Soft Front Panel to measure and the NI-SWITCH Soft Front Panel to close the analog bus relays.


DMM Soft Front Panel

Start>>All Programs>>National Instruments>>NI-DMM>>DMM Soft Front Panel


3. Can you measure the resistance when r0+ is connected to ab0+ and r0- is connected to ab0-?


If everything works with the SFP, then the problem may be related to the LabVIEW VI. 


Best regards,


Chad Erickson

Switch Product Support Engineer


Message 10 of 16