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HP48 I/R comms with PC? - Printable Version

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HP48 I/R comms with PC? - Mark Edmonds - 06-08-2009

I've searched the forum on this but can't find anything.

I would like to try linking a 48 with a PC using IRDA. I think I know how to set the 48 OK but finding a solution for the PC is a bit unknown.

I see that today you can buy USB IRDA adaptors. Here is an example:


Has anyone ever used one of these? How do they appear as a device within Windows XP? Are they another serial port (in which case, I presume tranfer is quite simple)?

I know that using IR is much slower than cable but for logistical reasons, using IR is more convenient for me than a serial cable.

Grateful for any sage words on this please!



Re: HP48 I/R comms with PC? - Christoph Giesselink - 06-08-2009

The communication between a HP48 and a PC over an IrDA adapter was a topic in the usenet comp.sys.hp48 years ago.

From this time there's a summary of my experinces published at http://www.hpcalc.org/details.php?id=4856.

For further information look at the discussions at comp.sys.hp48 please.



Re: HP48 I/R comms with PC? - Mark Edmonds - 06-08-2009

Thanks for your help Christoph :)

Having looked at the documentation for a couple of these current adaptors, there might be a major problem in WinXP anyway. It seems that in Win 9x, the IrDA gets installed as a new serial port so presumably, it wouldn't be a problem to get old programs like the serial link kit to communicate over it. However, in W2K and XP, the IrDA device appears to be a new device class in its own right so how you would get an old DOS program to talk over it is beyond my knowledge.

Bearing in mind the problems you highlighted in your own research, I'll have to pass on this one. Aside from the fun of doing comms over IR, the main reason I wanted to use this technique was to save having to route a lengthy serial lead from the machine room through a badly accessible cable duct.


Re: HP48 I/R comms with PC? - Marcus von Cube, Germany - 06-09-2009

This web page may help: http://www.ircomm2k.de/English/

IRCOMM2K is a virtual COM port driver for W2K and XP. The last update is five years old. But how old is our equipment? ;) So you could at least give it a try!

Re: HP48 I/R comms with PC? - Frank Rottgardt - 06-09-2009

Did not check the link nor did I read the articles. Wonder if it is possible to link up an HP-28s with a PC (Windows XP) using the internal IR-link? I might be wrong, but I guess I read somewhere that HPs IR-protocol is not compatible with the usual industry IR standard? Do one need special receivers or "translation" software?

I know about the HP-28s COM but are not keen on opening my beloved calculator. IR would be more comfortable. Maybe a dumb question: is the 28 IR-link one-way only? (send)

Re: HP48 I/R comms with PC? - Marcus von Cube, Germany - 06-09-2009

The HP-28s IR port is transmit only with a proprietary protocol, understood just by the printer (or the HP-48 with special software). So no way to use it for general communications.

The later models have a bidirectional IR port that can talk IRDA. As far as I know not the OBEX protocol for file exchange but the IRCOMM serial port emulation. X-Modem and Kermit are running on top of IRCOMM.

Re: HP48 I/R comms with PC? - Christoph Giesselink - 06-09-2009

Like Marcus wrote, the HP28S build in IR protocol for the HP82240 printer isn't compatible with "normal" one.

Nevertheless the HP28S has full support to execute self written assembler code. So it's possible to write your own protocoll by directly accessing the IR-transmitter LED. But you still have the same problem finding a capable IR-receiver on the PC side.

So to your last question, yes the HP28S supports only one way IR-communication by default.

But the hardware port inside the HP28, which controls the IR-LED, is bidirectional. I opened a HP28S, removed the IR-LED and connected a simple hand made signal level adjuster with a COM port interface to the calculator. With self written assembler software on the calculator I'm able to do serial communication with 2400 baud in both directions.



Re: HP48 I/R comms with PC? - Frank Rottgardt - 06-10-2009

So with this in mind one can only wonder why the he.. HP did not decide to implement this bidirectional IR when the were going from 28C to 28S (as last chance)? Almost everything was there.
Would have been a simple and cheap? way to introduce communication possibilities. Would it have been to much work to rewrite the IR-functions and add a new IR tranceiver? How many of us did not see KB of programs vanish when batteries were changed, without any possibility to get it back. I still can feel the sweat every time the battery indicator came up :-(
I am convinced many of the 28s users would gladly have given away some dollars for a special PC-IR-link if only HP had made one. Maybe HP did not want potential 41 customers to go for a HP28-"IR com" (so I am not sure when the 41 has been put out of production)

Re: HP48 I/R comms with PC? - Mark Edmonds - 06-10-2009

It never ceases to amaze me how much skill and thought so many of you apply to your HPs. Some of the things you do are so beyond anything I can think of, it is on a different level!

With the RPL machines for example, the kick for me is becoming expert at UserRPL and writing the most elegant code possible within the supplied confines. For the rest of you though, a task like controlling the rods in a nuclear power station with your HP48 represents a worthwhile achievement!