From jthornto@fs1.ee.ubc.ca Fri Jul 13 09:15:38 1990
From: jthornto@fs1.ee.ubc.ca (THORNTON JOHAN A)
Newsgroups: comp.sys.handhelds
Subject: Re: HP48SX: pin assignements and dumb question
Date: 7 Jul 90 02:31:36 GMT
Reply-To: jthornto@fs1.ee.ubc.ca (THORNTON JOHAN A)
Organization: Dept. of Electrical Engineering University of B.C.


Here are the pinouts for the 48SX serial port:



                  4 3 2 1
     /------------|-|-|-|----\
    |   48SX                  |    Pin   Function    Standard RS232 pin eqv.
    |   ___________________   |                       (25 pin connector)
    |  |                   |  |     1  Chassis Ground       1
    |  | 4:         "THIS" |  |     2  Transmit Data        2
    |  | 3:           "IS" |  |     3  Receive Data         3
    |  | 2:          "THE" |  |     4  Signal Ground        7
    |  | 1:       "SCREEN" |  |
    |   -------------------   |
    |                         |
    | [A] [B] [C] [D] [E] [F] |
    | MTH PRG CST VAR  ^  NXT |
    |     .  .  .  .  .  .    |

If you're making a cable, just make a standard null modem cable.
(reverse RX and TX)

      48SX pin           RS232 pin

   CHG   1  - - - - - - - -  1  CHG     Chassis ground does not
                                        actually have to be connected.
    TX   2  ------\ /------  2  TX
                   X
    RX   3  ------/ \------  3  RX

   GND   4  ---------------  7  GND


I have a problem with my cable: the PC won't receive data from the HP.
Anybody have any ideas?  The loopbacks work on both sides.  I think it
may be a problem with signal levels - the HP supposedly doesn't use
standard RS232 voltage levels.  A line driver could be installed to raise
the voltage.  Netters?

.sig
>Johan Thornton
>UBC Electrical Engineering

Path: santra!tut!sunic!mcsun!uunet!ogicse!caesar.cs.montana.edu!uakari.primate.wisc.edu!zaphod.mps.ohio-state.edu!tut.cis.ohio-state.edu!ucbvax!hplabs!hp-pcd!hpcvra!prestonb
From: prestonb@hpcvra.CV.HP.COM (Preston Brown)
Newsgroups: comp.sys.handhelds
Subject: HP 48SX serial I/O pinout
Message-ID: <21580018@hpcvra.CV.HP.COM>
Date: 12 Mar 90 22:50:36 GMT
Organization: Hewlett-Packard Co., Corvallis, OR, USA
Lines: 13


The following table shows how the 48SX 4 pin, the cable's 9 pin 
connector and the 25 pin adapter provided with the MSDOS PC link 
package are wired.

HP48SX                  IBM 9 PIN               IBM 25 PIN
(From the outside->in)
SHIELD-------------------  SHIELD----------------  SHIELD
TX (Output)<-------------2 RX (Input)------------3 RX (Input)
RX (Input)-------------->3 TX (Output)---------->2 TX (Output)
SGND---------------------5 GND-------------------7 GND

Preston