Table of contents
Section 1 Introduction.......................................................................5
This manual........................................................................................ 5
Intended audience.............................................................................. 5
Product documentation.......................................................................6
Product documentation set............................................................6
Document revision history............................................................. 6
Related documentation..................................................................7
Symbols and conventions...................................................................7
Symbols.........................................................................................7
Document conventions..................................................................7
Section 2 Modbus overview............................................................. 9
Modbus standard................................................................................9
Serial communication.................................................................... 9
Ethernet communication................................................................9
Application data implementation .................................................10
Terms and definitions.................................................................. 10
Documentation............................................................................ 10
Section 3 Vendor-specific implementation..................................... 13
Protocol server instances................................................................. 13
Connection to clients................................................................... 13
Protocol server attachment to a client......................................... 14
Several identical client connections.............................................14
Protocol data mapping to server instances................................. 14
Modbus link alternatives................................................................... 15
Serial link.....................................................................................15
Modbus serial link parameters............................................... 15
Modbus serial diagnostic counters......................................... 17
Troubleshooting serial communication...................................17
Character framing in different serial link modes..................... 18
TCP/IP link...................................................................................18
Modbus TCP/IP diagnostic counters...................................... 19
Supported Modbus function codes................................................... 19
Application functions....................................................................19
Diagnostic functions.................................................................... 20
Exception codes.......................................................................... 21
Modbus application data...................................................................21
Modbus data objects................................................................... 21
Modbus data implementation...................................................... 22
Table of contents
620 series
1
Communication Protocol Manual
