Communicating with PEM

[Dedalus7]

Has anyone written a LABView program to communicate with a Photoelastic Modulator (PEM) from Hinds Instruments?  I have a very old LabWindows/CVI [C for Virtual Instrumentation] program that does this by sending the command "AO_VWrite (device_number, chan, voltage)" to the PEM.  AO_VWrite scales the voltage to a binary value and writes that value to the DAC in the analog output channel, which is wired to the PEM Controller.  (I think.)  The voltage is related to the wavelength of the light we're interested in and the PEM Controller interprets it as such.  It uses the input to send the proper electrical signal to the modulator head.

I'd like to accomplish this in LABView 8.5.1.  I'm communicating with the PEM Controller over a serial port.  Can I write the wavelength directly to the PEM using VISA Write (as a string)?  Not sure if it would know how to interpret this.  I'm guessing it needs a voltage.  How can I immitate the AO_VWrite command in LABView?

Many thanks!

Andrew

[Sputnikrent]

Hi Andrew,

The AO_VWrite command you are referring to is a command for NI Data Acquisition devices, and would not work for third party instruments.

You will need to use VISA in order to communicate with the instrument via serial. Are you familiar with the commands that you will need to communicate with the PEM controller? These are usually pretty well detailed in the manual.

There is more information about instrument control here and here. Let us know how it goes!

[Dedalus7]

Thanks, Rasheel!  I'll check it out.