I found an instrument driver for the Solartron 1260 Impedance/Gain-Phase Analyzer by searching for "Solartron" under Option 3 of ni.com/support. I am attaching the initialization VI here as it is specific to the instrument being communicated with. This is assuming that the 1250 is uses the same communication techniques as the 1260 (it probably does.) Here is an excerpt from the documentation included with the VI:
NOTE: This instrument driver requires that the rear panel switches F1 & F2 are both turned to the "OFF" position. The driver uses the Line-feed character "\n" as the command terminator and will not operate correctly if the instrument is not configured properly.
Also, I noticed that this initialization VI assumes that the measurement device is confi
gured to respond at GPIB primary address 2.
I would suggest trying this simple configuration VI to see if you can basically communicate with the device. You can also use it as a basic template for how to write LabVIEW code to control the device.