View Full Version : Network Variables exchange From PDM to third party controller via UDP Protocol

05-28-2009, 01:52 PM
Here is a little Tip you should know when exchanging data from a PDM to a third party controller via Global Network variables.

If exchanging data between two PDM, no issues as the PDM is a CODESYS UDP protocol compatible.

In my case I was communicating with a Siemens CPU. So basically what happened, was when I was streaming data out the Siemens PLC, this one was able to receive my data but had to include in the reception buffer 20 bytes for the reception of the header information.

On the other direction when the Siemens PLC was streaming the data to me I could not see it. Just because the header from his data stream was not recognized as a CODESYS UDP protocol.

The only way for the PDM to see the Siemens PLC data was to have the Siemens PLC send 20 bytes of data before to emulate the CODESYS UDP header for me to see the data. The attached PDF received from Codesys Support people in Germany will describe how to generate the header information.

I believe this will work for any third party PLC not compatible with CODESYS UDP Protocol.

Hope it Help.

David Vieira.