I have a Tenney Sr. with VersaTenn III controller that I need to control via RS232. I am developing an application to control the VersaTenn III using Visual Basic 2005 and National Instruments Measurement Studio 8 ( VISA ). When I issue the command "= SP1 100" the controller works fine and sets the Set point to 10.
However, when I issue the command "? SP1" or "? C1" the controller times out and I do not get a returned value. Is there something I'm missing? Obviously the baud rate, data bits, parity... are set correctly or the first command would not have worked.
But for some reason the controller will not respond when I query for the current Set Point or Actual Temperature.
