PLC Programming

9 - DDE Communication with CoDeSys
9 DDE Communication with CoDeSys
CoDeSys has a DDE (dynamic data exchange) interface for reading data. CoDeSys uses this
interface to provide other applications that also use a DDE Interface with the contents of control
variables and IEC addresses
If the GatewayDDEServer is used, which works with symbols, CoDeSys is not needed to read
variables values from the PLC and to transfer them to applications with an DDE interface.
Attention: Direct addresses cannot be read over the DDE server ! For this case you have to define
variables in CoDeSys which are assigned to the desired addresses (AT).
Attention: The DDE interface has been tested with Word 97 and Excel 97 on Windows NT 4.0. If the DDE
communication fails caused by a mismatch of other versions or additionally installed programs on a
computer, 3S – Smart Software Solutions cannot take any responsibility.
9.1 DDE interface of the CoDeSys programming system...
Activating the DDE Interface
The DDE interface becomes active as soon as the PLC (or the simulation) is logged in.
General Approach to Data
A DDE inquiry can be divided into three parts:
1. Name of the program (here: CoDeSys),
2. File name and
3. Variable name to be read.
Name of the program: CoDeSys
File name: complete project path (c:\example\example.pro).
Variable name: The name of a variable as it appears in the Watch and Receipt Manager .
Which variables can be read
All addresses and variables are readable. Variables or addresses should be entered in the format
used in the Watch and Receipt Manager
Examples:
%IX1.4.1 (* Reads the input 1.4.1*)
PLC_PRG.TEST
(* Reads the variable TEST from the POU PLC_PRG*)
.GlobVar1 (* Reads the global variable GlobVar1 *)
Linking variables using WORD
In order to get the current value of the variable TEST from the POU PLC_PRG through the DDE
interface in Microsoft WORD, a field (e.g., the date) must be inserted in WORD ('Insert' "Field"). Now
when you click on the field with the right mouse button and select the command "Toggle Field Codes"
you can change the field function for the chosen text. In our example, this would look as follows:
{ DDEAUTO CODESYS "C:\CODESYS\PROJECT\IFMBSP.PRO" "PLC_PRG.TEST" }
Click on the field with the right mouse button again, then click on "Update Field" and the desired
variable content appears in the text.
Linking variables using EXCEL
The following must be entered in Microsoft EXCEL before you can assign a variable to a cell.
CoDeSys V2.3 9-1