Setting GPIB primary address 31

[Mike_D.]

I'm adding a GPIB interface to my existing VC++ 6.0 Windows app using NI's NI-488.2 device driver. I understand that valid primary addresses (PAD) are 0 to 30. However, I have one customer with an HP8569A that expects to plot to GPIB PAD 31. This address is evidently hardcoded into the 8569A with no way to change it.

If I try to set PAD 31 in NI-488.2 I get an EARG error, which is understandable. My question is this: Can I set PAD 31, ignore the error produced, and have NI-488.2 respond to PAD 31 data? In other words, would NI-488.2 respond to PAD 31 the same way it would respond to say PAD 30?

Thanks,
Mike

[NI-488.2 master]

I'm not sure that this is possible. What addressing command byte does a device at PAD31 expect? When addressing a device at PAD30 to listen, NI-488.2 will send 0x3E. The command byte that would be associated with making PAD 31 listen is 0x3F. 0x3F is called the "unlisten" message. This will cause all devices addressed to listen to transition out of the listening state.

I know that NI-488.2 will not handle the PAD 31 device, nor do I know how any other driver could handle it. You could try using board-level calls and do the addressing yourself with ibcmd.

Is the device possibly using secondary addressing? Is it possibly using PAD 30 with SAD 1?

Craig A
National Instruments Engineer