Are wanting to remotely control the SR844 or just read back signal? Your question is a bit vague or confused.
The SR844 has analogue output which you can capture with you daq by wiring to its AI. You can thus digitise your analogue signal and save the data to a file.
But you daq cannot make use of rs232 or GPIB interfaces to communicate with and control settings on the instrument. For that you need a serial cable from instrument connected to serial port on the pc, a serial/usb adaptor if you don't have serial port on pc, or a GPIB cable and card or a gpib-usb connected between instrument and pc.
Hope that helps.
