DB9F pinout voltage <5V


The voltage across the following pins is <5V and I’m no longer able to speak to slaves when connected to my AB7072. Is the unit damaged?

Kind Regards,



What is the voltage on the line right now?


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Hi Kevin,

It’s 4.25V currently

The low of a drop should not affect the device communication.

What is the current LED status of the unit?

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I should add the slave device and cable are both working, and I can speak to the AB7072 over Ethernet.
All that remains is the Serial port…


The subnet is red but the others are healthy.
If I have inadvertently damaged the serial transceivers during wiring, how could I tell?


If everything is configured correctly, and no communication is occurring, then it could be a damaged module.

I would create ticket to proceed with a possible RMA.