Why can't I talk to an instrument at GPIB address 21?

[dimitrig]

It's possible that your GPIB adapter is using the same address. Each device on the GPIB bus requires a unique address, including the GPIB adapter. It is known that Agilent GPIB adapters use GPIB bus address 21, which will cause problems when talking to an instrument with the same address.

With some GPIB adapters, the address may be changeable, with others it may not. The simplest solution is usually to avoid using the same address, as the one of your adapter, or other reserved addresses for an instrument address.

For more information, please read the corresponding ICE help topic.