A problem with digital output channels with Ni 9375

[engahmedtg]

Hello ,

I just purchaed two NI 9375 Digital I/O modules, They are connected to a 9174 USB chassis. 

One of them is working perfectly but I have a problem with the Digital output channels of the other one. I'm connecting a 15 V supply so when the channel is on it passes the 15V to the load while when it is off it still passes some voltage to the load which is around 7 V. This problem is in all DO channels.

 please  let me know if you ever met this problem.I preferred to ask before shipping it back,

[Buechsenschuetz]

Maybe there is a problem with leakage current. The output voltage is very probably switched by FET transistors, and these have - different from a relay - always some leakage current. Are you measuring the voltage in OFF state with the load connected or just with a DVM? With the high input impedance of the DVM, the minor leakage current might cause a noticeable output voltage but this voltage should break down to zero if a significant load is connected.

I could not find any specs for leakage current, also I do not have an explanation why you see this on just one board.

[000011101010]

I am having the same issue, and the only difference is I am supplying 12V to Vsup. Did you ever resolve this? Did you simply return the card to NI?

[patrick.o]

Could you clarify what you are expecting to see, and what you are currently seeing? It seems that the original poster was trying to output 2 digital signals, 1 from each of his NI-9375 modules. Is this similar to what you are trying to achieve?

Also, if you strongly believe your hardware isn't working properly, you may want to consider calling our customer support line and creating a service request.

[000011101010]

I would expect to see <0.5V or very close to 0V when the outputs are in the off state, not +7V. I did try calling NI customer support, but because I have a basic VLA they would not direct me to phone or email support; so, I turned here to the forums.

[patrick.o]

What do you have connected to the 9375? Is it just the power supply or are there other devices? Can you tell more about how you have the module wired and what it's wired to?

Also, have you checked the current in the device to see if it is within the maximum allowable current? The Operating Instruction and Specifications guide has more information on how to calculate this based on your set up to ensure the current in the device isn't exceeding its specifications.

NI 9375 Getting Started Guide

http://www.ni.com/pdf/manuals/374644c.pdf

[nicola.g]

Hi everyone,
have you solved the issue? I've the same problem with the 7V in the digital outputs. I think that all the linkage are correct but still doesn't work. 
Thanks!

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@patrick.o

[smokes]

Have you checked your Ground connection? Common Ground?

[MauraW]

NI 9375 DIO Module  the Vout is not 0V at a Low but its Vout = Io x Ro

See: Troubleshooting Digital Output and Pulse Generation NI C Series Devices

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z000000P8gGSAS&l=en-US

[LogeshKumar453607]

Hello, Use 10K resistor across DO line wrt COM. it can act as pull down resistor which solves your issue. it is because of DO lines has high impedence.