Communication issue between HMI and PLC

Hi,

I have a S7-300 plc and wincc flexible HMI,connected with profibus, the issue is when i press a start button from HMI panel, operation starts in normal condition(We have configure diffrent start button for diffrent operation e.g. Agitator, Scrapper, Homoginiser, Heating & cooling ). But after some time the operation abort automatically, after that if i press start button, it dosen't start operation,and this happen to all the start button, i cant start any  of the above mentioned operation, but after 10 to 15 minutes when i press start button it again start and runs for some time and stop. We have not configured any timer in the logic as this is continuous process and we can start & stop accordingly.

Kindly Help

Thank you,

Gaus

Hello GAUS123

I think there is some Overwriting issue in the PLC Program because a SetTag function or another Function does only set a rising edge or a Value change and no remaing Signal to the PLC.

So Do the test with an Interface DB. So the Signals from the HMI into a seperate DB. Then you can see if the PLC can set the Signals. I think you overwrite the signals somewhere in the PLC Program.

I Had a lot of these Issues with our Customers. In almost every case the HMI was not the Error.

Bye Murof

Hi Gaus123, 

Just a random idea here. May be you can think of using a button mode instead of a switch mode for operation? 

Button mode: Pulse start to start , pulse stop to stop. 

Switch mode: Latch Start =1 to start, Latch start = 0 to stop. 

Hope it helps. 

Hello

I think a Toggle Button is also not the right thing.

There are often Users that use for single switching a set at press and reset at release of the Button. That can cause a lot of timing issues and Problems if you use In/Out Parameters and so on ..

I have the best experiences with a setBit (or SetTag) to trigger something in the PLC. Then if the PLC gets this rising edge or Value change then the PLC can do a Reset or setting Initial Value. Then you have a clear handshake.

Bye Murof