TOHO ELECTRONICS TTM200 - Manual (Page 35)

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8. Specifications
8.1 Communications standard category
Compliant with EIA standard RS-485
8.2 Communications specifications
8.2.1 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)
8.2.2 Interface system
Signal line: ..................................... 2 lines for transmission and reception
Communications speed: ................. 2,400, 4,800, 9,600, 19,200 and 38,400 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.
8.2.3 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.
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.
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)