Using variable length with Siemens CP343

I need some help to creat a communication where I can receive TCP/IP telegrams with variable length on a Siemens CP343-1 ethernet-card.

I have already tried to read the first 2 bytes (which contain the telegram length) with one block (I use AG_RECV), and then creat an any pointer with this length for the next receive block, this works fine until I send a new telegran with another length. Then my receive blocks lockup, and I have to put them into stop and run again i order to get the communication working again.

Do anyone know if it is possible to reset the communicationsblocks from the PLC program??

Or do anyone have any exampel for this type of problem??

I know that Siemens recomend that you always use fix length telegrams, and we normally do this, but in this case our customer wants to use variable length telegrams.

Christian

Hi,

this is what I've found on Siemens-supportsite:
http://support.automation.siemens.com/WW/view/en/8707570

Maybe the decription points you in the right direction.
There is a sample, but it's not free. It's charged
software.

cheers
Rolf

Thanks Rolf

I have been quite busy at work with other things on the machine, so I didn't get arount to look at your link until today, I think that the proposal that Siemens makes, can't be used because they are using 4 starts bytes, but mabey it can, I have only looked at the describtion.
I don't have any credit to buy the example.

I will keep working on my previos solution, since I found another example here in this forum.

But once again thanks anyway.

Christian