Software Description
ComTec GmbH
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5.3. Controlling the MPA4 Windows Server via DDE
The MPA4 program can be a server for DDE (Dynamic Data Exchange). Many Windows software
packages can use the DDE standard protocols to communicate with other Windows programs, for
example GRAMS, FAMOS or LabVIEW. In the following the DDE capabilities of the MPA4
program are described together with a demo VI („Virtual Instrument“) for LabVIEW. It is not
recommended to use the DDE protocol for LabVIEW, as also a DLL interface is available that is
much faster. The following should be seen as a general description of the DDE conversation
capabilities of the MPA4 program.
5.3.1. Open
Conversation
application: MPA4
topic: MPA4-
Any application that wants to be a client of a DDE server, must open the conversation first by
specifying an application and a topic name. The application name is MPA4 and the topic is
MPA4-.
5.3.2. DDE
Execute
The DDE Execute command can be used to perform any action of the MPA4 program. Any of the
Control command lines described in section 5.2 can be used. For example a sequence of control
commands saved in a file TEST.CTL can be executed by specifying the command
RUN TEST.CTL
The MPA4 program then executes the command and, after finishing, it sends an Acknowledge
message to the DDE client. This can be used to synchronize the actions in both applications.
Fig. 5.27: Opening the DDE conversation with the MPA4 in LabVIEW