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