GPIB Addressing

All devices and boards connected to the GPIB must be assigned a unique GPIB address. The Controller uses the addresses to identify each device when sending or receiving data. A GPIB address is made up of two parts: a primary address and an optional secondary address. You usually set the address using switches on the board or device.

The primary address is a number in the range 0 to 30. The GPIB Controller uses the primary address to form a talk or listen address that is sent over the GPIB when communicating with a device.

A talk address is formed by setting bit 6, the TA (Talk Active) bit of the GPIB address. A listen address is formed by setting bit 5, the LA (Listen Active) bit of the GPIB address. For example, if a device is at address 1, the Controller sends hex 41 (address 1 with bit 6 set) to make the device a Talker. Because the Controller is usually at primary address 0, it sends hex 20 (address 0 with bit 5 set) to make itself a Listener. The following table shows the configuration of the GPIB address bits.

With some devices, you can use secondary addressing. A secondary address is a number in the range hex 60 to hex 7E. When secondary addressing is in use, the Controller sends the primary talk or listen address of the device, followed by the secondary address of the device.