VISA Write Timeout

[Sean Reminga]

I am using LabVIEW 7 to send serial commands to a motor controller
using XON/XOFF flow controll. Occationaly my equipment sends the byte
to turn off the serial transmission and I believe this is when the
VISA Write timeout occurs. My problem is when this timeout occurs, in
order to restart serial communication I have to completely close
LabVIEW. If I do not close labview and just restart my program which
runs my initalization VI the it will continue not to write.

Thank you for your help

Sean Reminga
Purdue PRIME Lab
reminga@purdue.edu

[RJay]

Have you tried wiring the error out from the VISA Write to a Case Statement where the case Error causes a "Break at Serial Port.vi" and where the No Error cases simply wires through?

The idea is to send a break to the serial port and hopefully recover without having to close LV in order to regain control of the port.

[Dan_Mondrik]

In a similar way, if your instrument doesn't recognize the serial Break, you might try toggling the RTS and DTR lines. That's one of the main things VISA does when you close and reopen the port, and many older devices will see those 2 lines as a way of indicating that the connection is alive - assuming you're not using hardware flow control.

Dan Mondrik
National Instruments