User manual

IEC61131 User and Reference Manual
April 22, 2008
87
Modbus/UDP
Modbus/UDP communication mode is similar to Modbus/TCP communication mode. It has
the same message format with the Modbus/TCP. The only difference between them is one
uses TCP protocol and another uses UDP protocol.
 To configure a Modbus/UDP protocol connection, highlight Modbus/UDP in the
Communication Protocols window and click the Configure button. The Modbus/ UDP
Configuration window is displayed.
 To select a configured Modbus/UDP protocol connection, highlight Modbus/ UDP in
the Communication Protocols window and click the OK button.
 To close the dialog, without making a selection click the Cancel button.
General Parameters
When Modbus/UDP is selected for configuration the Modbus/ UDP Configuration dialog is
opened with the General tab selected as shown below.
Figure 35: Modbus/UDP Configuration (General) Dialog Box
The Modbus Communication Settings grouping contains Modbus specific communication
settings including the addressing mode, the station address, the timeout interval as well as
the number of attempts.
The Addressing parameter selects standard or extended Modbus addressing. Standard
addressing allows 255 stations and is compatible with standard Modbus devices. Extended
addressing allows 65534 stations, with stations 1 to 254 compatible with standard Modbus
devices. The default is Standard.