GPIB with old Mastech Source Meter

[Daltech]

Hi,

I'm trying to communicate with a Mastech Source-Meter through GPIB. We are using GPIB soubroutines in Visual Basic to communicate succesfully with Keithley source-meters, however the same code is not working with the Mastech. The instrument is old, very old, I'd say its about 20-25 years old.

We have an old DOS PC with a software program that can communicate with the Mastech however we don't have the sourcecode.

Why would this old PC and software program be able to commuincate with the meter while a new PC can't ?

We tried using an NI-Spy card to establish what was happening but it could only detect the handshaking that was going on, co commands were seen.

Hope you can help.

thanks

Ruairi

[LV_Pro]

The biggest thing to look into would be the speed that you are sending commands. Does it respond at all, perhaps the first command and none after. The actual underlying GPIB commands/protocol has remained fairly stable, with some enhancements in the last few years. The biggest in the last few years was the adoption of a number of manufacturers of the SCPI definition of standardized messages/commands, but this doesn't effect the underlying GPIB. Do you have the programming manual for the unit, to determine how the commands are formatted? It the command differences between older instruments and newer ones can be as simple as an ID? vs IDN?, but my guess is that if it works with an old  <100MHz PC and not with a newer one that speed/timing issues in the handshaking. You say that all you see with NI-Spy is hand shaking. How are you using it (obviously on the newer machine!). Is this when you are trying to use VB? When you say that you are using it to talk to one type of instrument, do you see the communications? If yes do you have the the Mastek addressed correctly, are you trying to use the same commands (they aren't probably the same, particularly if the newer units conform to SCPI). And if you could do a screen capture of the NI-Spy and send it (as a JPG, NOT bmp please!) it might help. And lastly, there are GPIB threads on another NI forum, where the denizens that hang out there are frequently very knowledgeable (that would be where the NI GPIB folks would most likely lurk!)

P.M.