S7 comms between PC and PLC

Hi there,

I am currently looking into ways to create a real-time connection between a s7-300 and a PC but am struggling to understand the benefits of ISO-on-TCP over TCP/IP. We have used opc previously but we now need to send and receive data faster.
I have got both to work using ag_send and ag_recv blocks. When i use TCP/IP I can create multiple connections to the PLC using different port numbers.
However when I try multiple connections using ISO-on-TCP it only allows one connection.

Is it worth using ISO-on-TCP over TCP/IP connection and how do I setup multiple ISO-on-TCP connections?

Thanks
Rob

How much data ?
How fast are you after ?
What kind of hardware is there EXACTLY. This greatly influences the possibilities.

However when I try multiple connections using ISO-on-TCP it only allows one connection.

Click to expand...

Are you configuring multiple connection ID's in NetPro, or are you trying to establish multiple send/receive jobs with the same connection ID ?

Its difficult to say how much data but i would guess maybe 80 words worth every sec, maybe not all in one go but as fast as possible preferably.

I'm using an old 315 at the moment with a CP343-1 but eventually it will be a 416 with corresponding CP.

I am configuring multiple id's in netpro but I don't have an application on my pc that can send the appropriate telegrams so I'm just using hyper terminal

Don't suppose anyone else can help can they?

You can't compare communication speeds of an S7-300 with the communication speeds of an S7-400. The communication speed of the 300 CPU's are limited by siemens.

80 words each second with an 400 should not be a problem with either protocol.

i only know one difference between ISO and TCP. TCP is routable and ISO is not. I dont know if there is a difference in communication speeds between them.

Regards

Marsupilami