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Communications
This chapter introduces information regarding the communications ports of the PLC.
Through this chapter, the user can obtain a full understanding about PLC
communication ports.
Chapter Contents
4.1 Communication Ports ........................................................................................................4-2
4.2 Communication Protocol ASCII mode..............................................................................4-3
4.2.1 ADR (Communication Address) ............................................................................4-3
4.2.2 CMD (Command code) and DATA ........................................................................4-3
4.2.3 LRC CHK (checksum) ...........................................................................................4-5
4.3 Communication Protocol RTU mode................................................................................4-7
4.3.1 Address (Communication Address).......................................................................4-7
4.3.2 CMD (Command code) and DATA ........................................................................4-8
4.3.3 CRC CHK (check sum) .........................................................................................4-9
4.4 PLC Device Address.........................................................................................................4-11
4.5 Command Code................................................................................................................4-13
4.5.1 Command Code: 01, Read Status of Contact (Input point X is not included) .....4-13
4.5.2 Command Code: 02, Read Status of Contact (Input point X is included) ...........4-14
4.5.3 Command Code: 03, Read Content of Register (T, C, D)...................................4-15
4.5.4 Command Code: 05, Force ON/OFF single contact ...........................................4-16
4.5.5 Command Code: 06, Set content of single register ............................................4-17
4.5.6 Command Code: 15, Force ON/OFF multiple contacts ......................................4-18
4.5.7 Command Code: 16, Set content of multiple registers .......................................4-18
4-1