나 3 Communication Specification 
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3  Communication Specification 
Comm. protocol  Modbus RTU (16bit CRC) 
Connection type  RS485 
Application standard  Compliance with EIA RS485 
Max. connection  31 units (address: 1 to 127) 
Synchronous method  Asynchronous 
Comm. type  Two-wire half duplex (half duplex) 
Comm. distance  Max. 800m 
Comm. speed  2400, 4800, 9600 (factory default), 19200, 38400bps 
Comm. response time  5 to 99ms (factory default: 20ms) 
Start bit  1-bit (fixed) 
Data bit  8-bit (fixed) 
Parity bit  None (factory default), Even, Odd 
Stop bit  1, 2-bit (factory default: 2bit) 
 
 
It is recommended to use communication converter RS232C to RS485 (SCM-38I, sold 
separately), USB to RS485 (SCM-US48I, sold separately). Communication cable should be 
twisted pair cable for RS485 communication.