TNT4882 Programming Considerations Chapter 4
• If the host interface determines that the Controller sent the secondary address of the TNT4882, it issues the Valid auxiliary command, and the TNT4882 becomes addressed.
• If the host interface determines that the Controller sent the secondary address of another device, it issues the Nonvalid auxiliary command.
Implementing Three or More Logical Devices: Normal Addressing
The TNT4882 can implement three or more logical devices that use normal addressing.
This mode requires intervention from the host interface. Refer to the Talker function in the IEEE 488.1 standard.
Complete the following steps to implement three logical devices that use normal addressing:
1.
Choose the no-addressing mode by writing a 30 (hex) to the ADMR. The host interface stores the addresses of the TNT4882 external to the TNT4882.
2.
Set the following bits in Auxiliary Register F (AUXRF): DHATA and DHALA.
The following sequence of events then occurs:
• The Controller sends a talk or listen address to the GPIB.
• The Command Pass Through (CPT) bit sets (see ISR1).
• The TNT4882 performs a DAC holdoff.
3.
Wait for the CPT bit to set. CPT sets when the Controller sends any talk or listen address over the GPIB.
4.
Read the CPTR to determine whether the Controller sent one of the talk or listen addresses of the TNT4882.
5.
If the CPTR matches one of the talk addresses of the TNT4882, the following sequence programs the TNT4882 to be the addressed Talker:
• Write B0 to the ADMR.
• Write 30 to the ADMR.
If the CPTR matches one of the listen addresses of the TNT4882, the following sequence programs the TNT4882 to be the addressed Listener:
• Write 70 to the ADMR.
• Write 30 to the ADMR.
TNT4882 Programmer Reference 4-6 © National Instruments Corp.
