Re: RPN and HP-IL Message #3 Posted by nigel on 15 Dec 2000, 11:14 a.m., in response to message #2 by Philip
philip
Thankyou for the confirmation about the portable plus charger.
If you have the HPIL Spec and the HPIL IC Spec ( on Museum CDs) then you have most of the information already except for the front page which follows National's format. If you do want the full spec I could get it copied and sent to you. However I am away over Christmas till the New Year and not sure what my net access will be over that period.
Herewith is the full text of the emails relating to the HPIL/6811 etc. I tried the Kaminski link but it bounced. A further search of the Australian National University, Canberra might turn up something, or on 68HC11.
Email text:
Re : Networking 20 HC11 with a PC
Sylvain Bissonnette (bisson@CAM.ORG)
Mon, 24 Jul 1995 20:32:08 –0500
Marek wrote:
I don’t know WHAT you want from the protocol. A few years ago we implemented a ‘software HP-IL’ using 6805s and it worked fine, but we had certain assumptions (wanted group control, didn’t care about efficiency). Mail me if you want more details. Yes, you can get a HP-IL card for the PC.
Hi Marek,
Can you tell me more on your software HP-IL?
Thanks for your reply
Sylivian Bissonnette
Bisson@cam.org
Bisson@cam.org ! Check to the home of 68HC11
!WWW
Silvain Bissonnette ! http://www.cam.org/~bisson/
8382 DeFougeray !
Anjou, Quebec. !
H1K 1K6 !
CANADA !
Re : Networking 20 HC11 with a PC
Marek B. Kaminski (mbk113@rsphy1.anu.edu.au)
Tue, 25 Jul 1995 01:29:17 –0500
Hi Marek,
Can you tell me more on your software HP-IL?
Sylvain Bissonnette
Sure can;
GENERALLY the HP-IL is a serial HP-IB (BP-IB, IEEE488 etc). It’s a loop (physically and logically). You send something and you listen till it comes back, then you know that the loop is alive. THIS STOPS ALL ACTION if only one station on the loop goes down...........
The protocol requires transmitting 11-bit entities (we called them chunks), out of which up to 8 bits can be data. We implemented it as two bytes (16 bits) with 5 bits wasted. The software we wrote controlled all operations on the bus as well as in the ‘devices’, ie. things we wanted internetworked (power supply controllers / monitors).
Physically it was just RS232, TX, RX and GND. The controlling PC ran a PASCAL driver which orchestrated all actions.
As I stated we did not need or expect big bandwidth; we HAD to be able to address more than 1 device at a time and perform group control (triggering), so we had to use something from the control world and not communications world.
I know that RS232 is only a point – point connection, and we did not abuse it. Each station on the loop did data recovery / resending (this also affected throughput –software retransmission.......). So if you are desperate to have the network without extra hardware, this might be your choice.
Cheers, Marek.
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