repairing/testing 82161a IL issue using 82162a

[Paul Berger (Canada)]

When you use a HP-41 as a trace device it is dedicated to that function so you would need another HP-IL controller device to issue commends. Having a trace device would certainly be helpful in isolating where things break down.

The chip that handles the IL protocol would be the same in both devices, it would be the next level up, the microprocessor running the device, that would determine what commands it responds to and how.

If you have both the the printer and the tape drive in the loop does the printer function normally? If so that would suggest that the HP-IL chip in the tape unit is mostly functional as all traffic on the loop has to pass through the HP-IL chip. For the loop to even function it would suggest that the assigning of addresses has worked.

A transmit error would indicate that the packet sent out did not get back to the controller which would indicate that the device is not re-transmitting the packet, which would suggest a problem with the embedded controller in the tape unit.

The HP-IL development module would give you more commands that would be helpful to troubleshoot the problem, the HPIL interface alone is pretty limited. A more capable controller like a 71B or a 75 would also be useful.

Paul.