rslinx opc server program?

[Guest dita]

when use vb read a data(n7:1) from slc5/05 via rslinx opc server( vb program as client),the value dead( can not change with the real value) after program run two hours,but if I restart the vb program,it is good again.why ? thanks dita

[Chris Elston 79]

Sounds like the OPC link dropped out. Do you have a bit that is sort of like a "heart beat"? Generally when I have a software app running with a PLC, I have a bit in the PLC I cal "heart-beat" This keeps turning on and off and checks to make sure the software application is up and running and ready to take or send data. Also I've heard it keep the "links" alive and not to give up on your PLC ACK/NAK timeouts. Just a thought...