TOHO ELECTRONICS TRM-006A - Manual (Page 34)

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7. Specifications
7.1 Communications standard category
Compliant with EIA standard RS-485
7.2 Communications specifications
7.2.1 Communications system
Network: ........................................ Multi-drop system (up to 1 pair, 31 stations)
Direction of information: ............... Half duplex
Synchronization system: ................ Asynchronous
Transmission code: ........................ ASCII, 7 bit code, except for BBC data
(highest-level bit = 0 in 8-bit code)
7.2.2 Interface system
Signal line: ..................................... 2 lines for transmission and reception
Communications speed:................. 1,200, 2,400, 4,800, 9,600 and 19,200 bps and this product is
set to it.
Communications distance:............. 500m maximum
Provided that it varies somewhat depending on the cable and other ambient conditions.
7.2.3 Character
1) TOHO communications protocols
Start bit length: ......................... Fixed at 1 bit
Stop bit length: ......................... Either 1 or 2 bit is selected and this product is set to it.
Data length: .............................. Either 7 or 8 bit is selected and this product is set to it.
Parity: ....................................... No. Either odd or even is selected and this product is set to it.
BCC check: .............................. Yes or no is selected and this product is set to it.
Communications address:......... 1-99
2) MODBUS communications (RTU) protocols
Start bit length: ......................... Fixed at 1 bit
Stop bit length: ......................... Either 1 or 2 bit is selected and this product is set to it. (If
parity-equipped, fixed at 1 bit.)
Data length: .............................. Fixed at 8 bit.
Parity: ....................................... No. Either odd or even is selected and this product is set to it.
CRC-16 check: ......................... Fixed at yes.
Communications address:......... 1-247
3) MODBUS communications (ASCII) protocols
Start bit length: ......................... Fixed at 1 bit
Stop bit length: ......................... Either 1 or 2 bit is selected and this product is set to it.
(If parity-equipped, fixed at 1 bit.)
Data length: .............................. Fixed at 7 bit.
Parity: ....................................... No. Either odd or even is selected and this product is set to it.
LRC check:............................... Fixed at yes.
Communications address:......... 1-247
4) MODBUS communications (RTU/ASCII) function codes
03H (reading the contents of the holding register)
10H (writing the contents of two or more holding registers)