Trouble writing a program to send the command that reads voltage (:meas:volt[:dc]?)

Question

I am working with a Keithley 2001 multimeter. It connects through a prologix gpib-usb controller into serial port 8 and has a primary address of 16. I am having trouble writing a program to send the command that reads voltage (:meas:volt[:dc]?). Would anybody be able to give me a VS c# program that would do this?