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HP Forum Archive 16

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Sitecom USB-to-Serial adapter
Message #1 Posted by Thomas Okken on 18 May 2006, 2:00 p.m.

Hi all,

Encouraged by several recent posts about using USB-to-Serial adapters, to connect an HP-48 to modern PCs without serial ports, I went and bought such an adapter myself: a Sitecom (model number CN-104).
Just like the other users reported (for different models from different brands), it works well. Under Linux (Fedora Core 3), it is recognized automatically and shows up as /dev/ttyUSB0; I can upload and download to my HP-48G using C-Kermit, and I can download pictures from my Olympus D-340R (using gphoto2) as well.
On the Windows side (XP sp2), I had to install a driver (from the included CD-ROM), and then the adapter shows up as COM4. It is possible to make it show up as any COM port; COM4 is just the default (possibly because COM3 is my laptop's built-in modem). I could then use Olympus' Camedia Master software to talk to my camera.
I haven't tried talking to the HP-48G from Windows XP yet. Does anyone have suggestions as to what software to use? Is it possible to compile C-Kermit under Cygwin, or should I pony up the $48 for Kermit 95, or are there other good alternatives?

- Thomas

Re: Sitecom USB-to-Serial adapter
Message #2 Posted by Raymond Del Tondo on 18 May 2006, 2:17 p.m.,
in response to message #1 by Thomas Okken


you can use MS-DOS KERMIT,
which also works in a DOS box in XP.

An alternative wuld be GSZ,
which features X,Y,Z-Modem .



Re: Sitecom USB-to-Serial adapter
Message #3 Posted by Han on 18 May 2006, 3:17 p.m.,
in response to message #1 by Thomas Okken

Windows XP comes with Hyperterminal. That's what I use to do my file transfers when I boot Windows XP. There is an HP48/49 connectivity package from which first loads the HP48 with an xmodem server. From there, all file transfers are drag-and-drop via the PC.

Re: Sitecom USB-to-Serial adapter
Message #4 Posted by Marcus von Cube, Germany on 18 May 2006, 5:10 p.m.,
in response to message #3 by Han

The 16 bit Windows app Transfile48 works well, too. It opens two windows, one of which is local and the other is remote. Transfile48 uses Kermit as its underlying protocol and doesn't install any special software on the 48.


Re: Sitecom USB-to-Serial adapter
Message #5 Posted by James M. Prange (Michigan) on 18 May 2006, 7:03 p.m.,
in response to message #1 by Thomas Okken

Any Kermit-based application that works with your operating system and can use the ("virtual"?) COM port should work with any 48 or 49 series, except the 49g+. They all have both Kermit and Kermit Server built-in, although a rather basic version of them.

With the 49g+, you'd also have to convert to IrDA or USB. I've used the 49g+ with HyperTerminal and an RS-232/IrDA converter (with Win98SE supplying a virtual COM port), but haven't been able to get Conn4x to work with IrDA. Conn4x works with the 49g+'s USB, and I believe that applications for Apple and Linux operating systems are also available.

The 49 series (including the 48gII) has the Xmodem Server built-in. As far as I know, this Xmodem Server is unique to these HP calculators.

The 48G/GX/G+ has Xmodem built-in, but doesn't have Xmodem Server built-in, although an Xmodem Server library is available. For any application that expects an Xmodem Server, install the library.

The 48S/SX doesn't have Xmodem built-in, so to use an Xmodem-based application with it, you'd have to find (or develop) an Xmodem application, and in some cases, an Xmodem Server. Xmodem for the 48S/SX might be availabe at

All 48 and 49 series also have "Serial I/O" commands built-in, so you could always develop your own communications protocol, although for file transfers, that seems to me much like re-inventing the wheel. But note that the XON/XOFF software flow control capability was intentionally removed from the 49 series, so you'd have to be careful not to overrun the 255-byte input buffer. You might want to provide for error checking.

Working in assembly language, you can ignore the RPL input buffer and build a string in temporary memory, and then replace its bytes one at a time, as long as your routine is fast enough to check the UART again by the time the next byte arrives. Again, you might want to provide for error checking.

Besides HyperTerminal, HPComm, the Kermit-based "Connectivity Kit" for the 49G, works with any 48 or 49 series. See

To use Conn4x, the Xmodem-based "Connectivity Kit" for the 49g+, on a 48G/GX/G+, you'll have to install the Xmodem Server Library (included with Conn4x) on the calculator. This library doesn't work with the 48S/SX, although I suppose that one that does could be developed. Be sure to use only the most recent version (Version 2.2 Build 2353, as far as I know) of Conn4x, available at HP's site.


Re: Sitecom USB-to-Serial adapter
Message #6 Posted by Thomas Okken on 19 May 2006, 7:52 a.m.,
in response to message #5 by James M. Prange (Michigan)

I tried the Kermit-based connectivity kit, but I couldn't get it to work. There was clearly some attempt at communication going on (messages flashing in the calculator's display etc.), but despite quadruple-checking all communication parameters, I kept getting Could Not Connect To The Calculator type messages.

I then tried the latest Conn4x package from HP's web site. I was a bit worried about having to install a library on the 48G, but the process turned out to be painless (the documentation is good and the application even gives step-by-step instructions). The library takes up about 3500 bytes on the calculator but that's not a problem, since I only use the calculator occasionally and don't keep huge data sets or programs on it.

Conn4x works fine, so I'll stick with that (and continue to use C-Kermit under Linux).

Thanks to all for your advice!

- Thomas

Re: Sitecom USB-to-Serial adapter
Message #7 Posted by Han on 20 May 2006, 1:09 a.m.,
in response to message #6 by Thomas Okken

The problem with running kermit programs under Windows XP is that they are usually DOS-based applications. Since Windows XP rarely provides hardware permissions to the command prompt (supposedly like a DOS environment), you will unlikely be able to use these kermit programs. (Under the older version of Windows like 95 or 98, they should work just fine).

Re: Sitecom USB-to-Serial adapter
Message #8 Posted by Thomas Okken on 20 May 2006, 9:00 a.m.,
in response to message #7 by Han

I was referring to hpcomm, which is similar to Conn4x in that it provides an explorer-type user interface with drag and drop, but it uses the kermit protocol to talk to the calculator (unlike Conn4x, which uses xmodem).
According to the documentation, hpcomm should work on WinNT and Win2000 (as well as 95 and 98), but I couldn't get it to work on my laptop, which runs XP. I don't know if XP is the problem, or the fact that I was using a USB-to-Serial converter rather than a "standard" COM port (which my laptop doesn't have). I thought hpcomm looked rather buggy anyway; it appears that it hasn't been updated in years.

- Thomas

Edited: 20 May 2006, 9:26 a.m.

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