Serial communication with equipment stops working

[Jerther]

Hi!

 

We have a Vision 130 PLC connected to a piece of equipment which sends us data through RS232 serial communication. Everything works fine but the PLC stops seeing new data frames for no apparent reason. The only way I've found to get the communication back is to reset the PLC (power cycle). Then it's good to go for anything between 30 seconds and a couple of minutes.

 

Here is a small video showing what's happening in the serial buffer monitor:

 

http://screencast.com/t/Z307fIC6v4n

 

We've hooked up another monitor to the equipment and it never stops sending data frames. The PLC just does not see them until we reset it.

 

Any idea where to look?

 

Thanks!!!

[s.pratt]

Hello,

 

Is it possible to post you code, or send it into support@unitronics.com for review?

[Jerther]

Found it... In fact, there's a buffer for the protocol, and it needs to be periodically reset. There was a reset in our logic but it would not trigger, so the buffer kept on filling up until it was full and the communication stopped.

 

We made the necessary adjustments to our logic so the buffer reset would trigger.