What is recommendation needs to be followed for Compact NSX when Modbus Connection Linking Two Switchboards.
When the 2-wire Modbus RS 485 network is not contained within the switchboard, the 2-wire RS 485 isolated repeater module needs to be inserted between the Modbus network inside the switchboard and the Modbus network outside the switchboard.
The following figure shows a Modbus link connecting three switchboards A, B, and C via 2-wire RS 485 isolated repeater modules:
The rules below must also be followed:
Each isolated Modbus segment must include a polarization at one point, and a Modbus terminator at each end:
On the segment outside the switchboard, the line polarization and a terminator are usually integrated in the Modbus master, and a Modbus terminator (part number VW3A8306DRC) must be connected at the other end, i.e. on the last 2-wire RS 485 isolated repeater module (the one on switchboard C in this case).
On the segment inside the switchboard, the line termination (line polarization and Modbus terminator) is integrated in the 2-wire RS 485 isolated repeater module. A Modbus terminator must be connected at the other end, on the last Modbus communication interface module or other Modbus slave (on the last Modbus communication interface modules in switchboards A and B in this case).
L is the length of the main segment of the Modbus cable (excluding tap links):