Hi there,

I need to transfer about 8-kbytes of data from within WinCC project to an S7-300 PLC. The time interval of PLC requests for data is about 50 seconds. Let me say that WinCC project has other resource consuming monitoring and event logging jobs to do. While the data tranfer is an essential part of the process, it is important that it take place as efficient as possible such that not to restrain other activities.
So any recommendation for a fast data transfer is highly appreciated.

gratefully,
Arash

Dear thidalgo,

Thank you for the response.

Actually i have already used a set of 40, 200-byteraw tags to transfer these
data. Raw tags are filled with data in a VB-script which is triggered upon data
request by PLC.
An unsigned 32-bit tag is used as handshakebetween PLC and WinCC. PLC
makes requests for data by setting this tag to a specific value. WinCC resets
this tag to signal the PLC that data is ready in raw tags.
Data arewritten to Raw tags asynchronously (i.e. write without wait). And then
handshake tag is written synchronously (i.e. write with wait).
These writings takes about 7 to 10 seconds. In case when a heavily dynamized graphics screen is being monitored, the writings may take up to 12 to 15 seconds. Also the time difference between the moment the PLC sets the handshake tag to the moment the VB-script is being triggered is about 7 to 10 seconds. So the total time from the moment the PLC makes a request for data to the moment it receives data sometimes reaches to as long as 30 seconds which is too high.
Is it normal to have such high delays in data transfer with raw tags? Is there some thing wrong with the communication components?

gratefully,
Arash

WinCC server uses TCP/IP network with normal ethernet card to communicate with PLC. Let me say that i have tested the CP1613 industrial ethernet card but saw no difference. According to the network engineer,network's traffic islow.As i said, i'm using asynchrounous write for raw tags and then write synchronously to handshake tag in order to signal the PLC that the data is ready.