ASCII Comms with MTS Level Plus Monitor

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Thread Starter

bobwool

I have designed a custom driver using Visual Basic to communicate serially via expansion RS-485 ports to several MTS Levl Plus Monitors. Each monitor is wired directly to it's own RS-485 port on the PC. The driver sends a command then waits for the reply. If the reply is not received within 5 secs or the reply data is not what is expected, a timeout is recorded. The driver seems to run at 100% success rate for several hours, but over time (e.g. overnight) it tends to degrade and eventually none of the serial devices are communicating. I'm hoping someone might have some experience with writing custom drivers, especially with VB.
 
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kalpak dabir

never had such a problem with even 4 ports simultaneous with different protocols on a 200MMX. possibly due to your time out implementation (subtle bug). also chkout the service packs for VB, in VB5.0 that i am using the mscomm control was buggy and corrected in a later sevice pack.

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