Computer Interfacing
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RS485 Wiring - Voltage present!

Voltage present between +/- and ground


       Computer Interfacing Forum Index -> RS422 and RS485
Author Message
New User

Joined: 03 Oct 2012
Posts: 1
Location: Sydney Australia

Oct 03, 2012 6:35 am

I have a scenario where I have voltage present between the communication cores (+/-) and ground.
The equipment connected on the RS485 bus is electrical meters for monitoring.
This voltage is about 100V~.

Has anyone else experienced this type of scenario?
(Is it normal or does this sound like something wrong).

It does appear that the more meters connected, this voltage creeps up.
I discovered it by touch - it gave what felt like a static shock.

Voltage between +/- is as normal for RS485.

Thanks for any assistance.

Dec 01, 2013 2:54 pm

Sounds like you have unshieldet wirings. Use proper cable and put shield to ground from one end, no grounding in meters.

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