User Manual
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6. - RS485 COMMUNICATION PORTOCOL
6.1.- MODBUS © protocol
The composition of the RS-485 cabling must be carried out with a meshed screen cable
(minimum 3 wire),
diameter of not less than 0.5mm
2
, with a maximum distance of 1,200 m
between the motor protector and the master unit. This Bus may connect a maximum of 32unit.
Notes:
1.
For communication with the master unit, customers can choose the RS-232 to RS-485 converter
to use.
2.
Not all the PR200 with RS485 port, please check your ordered product to confirm if the meter
has remote communication function.
Due to product modifications or custom requirements, the interface pin place may be change. For
details, please refer to product label on the rear board
6.1.1- Modbus RTU Frame Format:
Address code
1 BYTE
Slave device address
1-247
Function code
1 BYTE
Indicates the function codes
like read coils / inputs
Data code
4 BYTE
Starting address, high byte
Starting address, low byte
Number of registers, high byte
Number of registers, low byte
Error Check code
2 BYTE
Cyclical Redundancy Check
(
CRC )