Communication Guide
Bus connection through a SCA type junction box
1.Master (PLC, PC or communication module)
2.Modbus cable (It is different according to the master side or a master having polarization combined to the other part of Bus)
3.Junction box
4.Modbus cable
5.Line terminators : 120Ω - 0.25W
Please use a cable with 2pair shieded twisted conductors for Interface protection.
It is adviced to isolate the Modbus cable 30cm(11.8in) at least from a power cable.
If necessary, intersect the Modbus cable to a power cable perpendicularly.
Refer to the diagram in the left side for the line terminator wiring.
2 wire MODBUS RJ45 connections
Pin on RJ45 | Pin on nEOCR | EIA/TIA 485 name |
4 | D1 | B/B’ |
5 | D0 | A/A’ |
8 | V- | C/C’ |
Pin ‘S’ can be used for shield wire connection.
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