User manual

IEC61131 User and Reference Manual
April 22, 2008
64
Modbus ASCII in UDP
Modbus ASCII in UDP protocol is similar to Modbus ASCII in TCP protocol. It has the same
message format as the Modbus ASCII in TCP. The only difference between them is one
uses TCP protocol and another uses UDP protocol.
 To configure a Modbus ASCII in TCP protocol connection, highlight Modbus ASCII in
UDP in the Communication Protocols window and click the Configure button. The
Modbus ASCII in UDP Configuration window is displayed.
 To select a configured Modbus ASCII in TCP protocol connection, highlight Modbus
ASCII in 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 ASCII in UDP is selected for configuration the Modbus ASCII in UDP
Configuration dialog is opened with the General tab selected as shown below.
Figure 18: Modbus ASCII in 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.