Thanx Collin and Scott for your suggestions. We could finally communicate with our device. It was a hardware problem, indeed. Sorry for the confusion!! Now we are working on controlling the power supply through GPIB.
Sada, glad to hear everything is working. Can you say what the root cause was? For the future benefit of others who may have the same or similar problem it is useful to list the steps taken to identify the root cause.
Hi Collin!! The actual problem was with one of the ICs on our device. We were using 74LS573 IC for external memory interfacing. We have written some random values to the count registers (cnt0 thru cnt3) of the TNT, but couldn't read them back correctly. Also we were unable to read the primary and secondary addresses from the ADR0 and ADR1 registers. We have checked the address lines of the IC and identified that one of the address lines wasn't functioning properly. When we have replaced the IC, everything was fine.
