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HP Forum Archive 13

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HP-71B/HP-41CX on same HP-IL Loop
Message #1 Posted by Jeff on 11 Aug 2003, 8:26 p.m.

HP-71B/HP-41CX on same HP-IL Loop, can this work? I presume so but I have been having problems getting the HP-71B or the HP-41CX to print or access the tape drive. I have checked the cables for continuity and also that each one works, prints and accesses the tape drive, while the other is not plugged in. I have been reading the HP-IL books for both machines and have yet to get anything that works. "Broken IL Loop" is one of the messages I get. Any thoughts or ideas would be appreciated. I would like to leave them both connected and just transfer control from one to the other when required. Best Regards, Jeff

Weird, isn't it?
Message #2 Posted by Vieira, Luiz C. (Brazil) on 12 Aug 2003, 12:17 a.m.,
in response to message #1 by Jeff

Hi, Jeff;

Because of the fact I had only one IL cable, one 9114B (IL disk drive) and the 82160A (HP41 HPIL ROM module), I tried this about a couple of months ago to see what happened.

The fact is that the HP71B (and anyone else) cannot be a controler in a loop where an HP41 is part of. If you put two HP41 in a loop (as Jose Ernesto once tried) they will conflict with each other because both will try to be controlers, and one of the rules in an HPIL loop is that only one controler can exist; all other devices are "talker" or "listener". I tried to go further and set the HP71 as a listener, but I believe it is set as a listener by the HP41. If you have the Extended I/O module (or any other taht is able to do it, like PANAME ROM) you can connect both the HP41 and the HP71 together (and only) and execute AID in the HP41. In the first attempt you'll read [TRANSMIT ERR] in the HP41, but in the second attempt you'll find no errors and the ALPHA register will contain [HP71 ] text after executing AID.

Try it and tell us. I cannot go any further because I did not try to.

Not too much of a help, but I think it's a starting point.


Luiz (Brazil)

Edited: 12 Aug 2003, 12:18 a.m.

Re: HP-71B/HP-41CX on same HP-IL Loop
Message #3 Posted by Philip on 12 Aug 2003, 8:02 p.m.,
in response to message #1 by Jeff

Try this with just the 71 and 41 connected.

on 71: CONTROL OFF @ RESTORE IO ENTER :LOOP;A$ @ DISP A$ (there must be a space before :)


That should send the string from the 41 to the 71.

I believe CONTROL OFF is the key to removing the 71 from Controller Status. You'll need to do a RESET HPIL or CONTROL ON on the 71 to regain loop control.

Hope that helps.

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