Schneider Electric EM3555 Manual Do Utilizador

21

© 2011 Schneider Electric All Rights Reserved.

The RS-485 slave port allows the power meter to be connected in a daisy chain 

with up to 63 2-wire devices. In this bulletin, communications link refers to a 

chain of devices that are connected by a communications cable.

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Belden 1120 A or equivalent (600 V)

120 Ω terminator 

on the first and 

last device of the 

daisy chain

Shield wire

•  The terminal’s voltage and current ratings are compliant with the 

requirements of the EIA RS-485 communications standard.

•  The RS-485 transceivers are ¼ unit load or less.

•  RS-485+ has a 47 kΩ pull up to +5V, and RS-485- has a 47 kΩ pull 

down to Shield (RS-485 signal ground).

•  Wire the RS-485 bus as a daisy chain from device to device, without 

any stubs. Use 120 Ω termination resistors at each end of the bus (not 

included). 

•  Shield is not internally connected to Earth Ground.

•  Connect Shield to Earth Ground somewhere on the RS-485 bus.

•  Use 14-24 gauge wire for all connections.

•  When tightening terminals, ensure that the correct torque is applied: 

3.5 - 4.4 in·lb (0.4-0.5 N·m).

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