Connecting meters with 3 RS-485 terminals to meters with 4 RS-485 terminals

[swil]

Hi,

We are looking to install a serial string with PM5350s, iEM3150s and iEM3350s. The customer has asked if shielded twisted pair is acceptable for the RS-485 connections.

I have read https://community.se.com/t5/Power-Metering/PM5300-vs-5560-3-wire-RS485-wiring-differences/m-p/86880  but remain unsure about combining old and new Schneider RS-485 connection types (3 terminal and 4 terminal) in a serial string.

Question:

Is it correct to specify Beldin 9841 (or equivalent) to daisy chain the the RS-485 meter connections, leaving the shield terminal unused on the meters where 4 terminals are available (0V, shield, D0- and D0+)? 

(Should the cable shield conductor be terminated to the shield connection on meters with three RS-485 terminals, terminated to the 0V connection of meters with 4 available RS-485 terminals, and grounded at a single point?)

Thanks for any assistance provided.

[Charles_Murison · Accepted solution]

Hello Swil,

"When wiring these older devices along with newer devices, the shield conductor of the cable should be landed on the 0V terminal of the newer device. This will leave the "shield" connection on the newer devices not connected which is fine."