Using the Modbus Ports

Two-Wire Cabling Schemes for Modbus RS485 Networks

Introduction

Two-wire cabling schemes may be used for single master/slave or multimaster/

 

 

slave communications. Masters may be located anywhere in the network.

 

 

CAUTION

 

 

 

POTENTIAL FOR MULTIMASTER CONFLICTS

 

 

 

Configure a multimaster network carefully to avoid masters issuing simultaneous or

 

 

conflicting commands to the same slave module.

 

 

 

Failure to observe this precaution can result in injury or equipment damage.

Length

 

 

The maximum length of cable from one end of network to other is 2000 ft. (609 m).

Number of

 

 

The maximum number of devices in a network is 64 if all are Momentum devices.

Devices

Otherwise, the maximum is 32.

 

Termination

 

 

One end of the cable run must be terminated with a terminating resistor (color code

 

 

is red).

 

 

 

The other end of the cable must be terminated with a terminating shunt, which

 

 

connects the transmit pair to the receiver pair (color code is blue).

 

 

 

 

 

 

Description

Part Number

 

 

 

 

 

 

Modbus Plus or Modbus RS485 Terminating RJ45 Resistor Plugs

170 XTS 021 00

 

 

(pack of 2)

 

 

 

 

 

 

 

Modbus RS485 Terminating RJ45 Shunt Plugs

170 XTS 042 00

 

 

 

 

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870 USE 101 10 V.2

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Schneider Electric Processor Adapter manual Two-Wire Cabling Schemes for Modbus RS485 Networks