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RS485 shield termination
  | Posted by jake  on 4 July, 2012 - 6:41 am |
I am working on a large network and was wondering the proper method in how to terminate the shield cable of an rs 485 cable. It will be used between a master and multiple slaves. I was guessing to terminate the shield on the master side but then what to do between slaves? I am not sure yet If I will be terminating on all of the slaves as well, or do I twist the shields of the two daisy chained cables together and tape them back? Honeywell network
| Posted by David  on 4 July, 2012 - 1:58 pm |
From National's AN-1057 note on RS-485
https://www.national.com/an/AN/AN-1057.pdf
Generally, a shield connects to a solid ground (normally, the metal frame around the system or subsystem) with a low impedance at one end and a series RC network at the other. This arrangement prevents the flow of DC ground-loop currents in the shield.
Me - I ground the shield at the master and tie the shields together at each slave and float them.
https://www.national.com/an/AN/AN-1057.pdf
Generally, a shield connects to a solid ground (normally, the metal frame around the system or subsystem) with a low impedance at one end and a series RC network at the other. This arrangement prevents the flow of DC ground-loop currents in the shield.
Me - I ground the shield at the master and tie the shields together at each slave and float them.
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