Ethernet UDP communication

Hello,

I will communicate with a device(non PLC) via Ethernet UDP. It is up to me to specify the protocol and the owner of the other device will implement this.

I use a CodeSys based PLC(Schneider SOMACHINE). I know that Network variables are based on UDP transfer. So I figure I might just go ahead and use Network Variables and life will be easy. But I find no documentation of the protocol for the UDP transfer of Network variables in Codesys. Can anyone help?

Schneider has done UDP communications with that platform before:

http://www2.schneider-electric.com/sites/corporate/en/solutions/oem/palladium-technologies.page

However, I would question the use of UDP. There are specific cases where it makes sense, but not sure that is the quickest/easiest path forward. If the Network Variables is not documented, maybe you should look elsewhere. In a vacuum, if the other end is flexible, I would just do ModbusTCP. It's well documented, native to the PLC platform so no custom communications protocols on one end, and libraries are available for the other end if desired. Since it is fully documented, they could implement a subset of the protocol anyway (just guessing) to reduce cost, time, and complexity.

So what are the real project constraints that drive you to UDP? What is the other system, and are there other options that might standard, rather than custom?