BENSHAW RSi SG Series, Instruction Manual

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Chapter 9 – RS485/Modbus RTU Communications
9-2
9.2 Specification
9.2.1 Performance Specification
Item Specification
Transmission form Bus method, Multi-drop Link System
Applicable inverter SG series
Connectable drives Max 31
Transmission distance Max. 1,200m (Within 700m Recommended)
Recommended wire 0.75mm
2
(12AWG), Shield Type Twisted-Pair Wire
9.2.2 Hardware Specification
Item Specification
Installation Use C+, C-,CM terminals on control terminal block
Power supply Use Insulated power from the inverter power supply
9.2.3 Communication Specification
Item Specification
Communication speed 19,200/9,600/4,800/2,400/1,200 bps selectable
Communication system Half duplex system
Character system
ASCII (8 bit)
Stop bit length 1 bit
Check Sum (CRC16) 2 byte
Parity bit None
Protocol supported
Parameter Read/Write, Monitoring parameter register/execution
Broadcasting
9.2.4 Installation
Connecting the communication line
1) Connect the Modbus-RTU communication line to the inverter’s (C+), (C-) and CM terminals of the control
terminals.
2) Connect the CM terminal among inverters for stable communication.
3) Check the connection and turn ON the inverter.
4) If the communication line is connected correctly set the communication-related parameters per the following
table:
5) Install a repeater to upgrade the communication speed or longer than 1200mm communication line is used.
Repeater is required for upgrading communication quality in the noise-high environment.