Modbus通信通讯教程(详细)

www.PLCworld.cn 1 Protocol Communication PLC Programmable Logical Controller PLC PLC Modicon PLC 2 Modbus Modicon PLC / / (1-1) / RS232C Ethernet 2.1 Bit Data Bit Parity Bit Stop Bit Byte Start z z Bit Byte www.PLCworld.cn z z z z z 1111001 (1-2) Start - Stop / / 1 Byte 1 0 0 Baud Rate 1 1 0 None Odd Even Parity Data Bits 5 6 7 8 Stop Bits 1 1.5 2 ASCII Code 7 ASCII 1 9600 bps (0) 1 7 8 ABC None 8 www.PLCworld.cn 1 0 7 ASCII 2.2 SDLC HDLC F 8 SYN 16 0x16 8 SYN SYN SYN (1-3) F (1-4) 1 8 8 www.PLCworld.cn 20% 48 HDLC 48 / 1048 * 100% = 4.6% 1000 Modbus PLC 2.3 Ethernet Ethernet Modbus Plus Modbus Modbus Broadcast Ethernet 48 Ethernet Frame 64 1518 CRC Check 8 6 6 2 46 - 1500 4 Frame type Data CRC (1-5) Ethernet Frame format TCP UDP Frame CRC Frame type CRC CRC Ethernet IP Address Station No. CRC Frame Ethernet Ethernet TCP/IP Windows Unix DOS API socket www.PLCworld.cn Modbus/TCP Modbus/232 socket RS232 CRC Frame 6 byte TCP 3 Communication Protocol 3.1 PLC PLC PLC Modicon Allen-Brandley Simatic Siemens Simatic TI PLC GE Mitsubishi MelsecA Mitsubishi FX2 OMRON Koyo (1-6) 3.2 Modbus Modbus 1979 1997 Modbus/232 Modbus Plus Modbus/TCP DF1 EtherentIP Profibus MPI Task Code SNP PC-Link PC-Link HostLink FINS U-01DM/G-01DM Ethernet TCP/IP Ethernet Ethernet Ethernet Ethernet Ethernet Modicon PLC Modbus Modbus/TCP Modbus Plus OSI