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Building the HP49G Serial PC-Link Cable
by E.Carta
Version 1.20
Warning: This is *NOT* a Hewlett-Packard official page. I assume no responsibility about any damage you could get by following these schematics.
1. Introduction.
In these pages you find several projects to build from yourself a fully-functional HP49G cable, without having to buy the original one. All the schematics and the projects are from me. With each of these cables you'll be able both to share software between the HP49G and your PC, and to perform the flash-ROM upgrading.
LCD SCREEN /|-----------------------------|\ | +---^-----------------+ | |____| ..... <pin 1 to 5 |____| | | ..... <pin 6 to 10 | | | \---------------------/ | \-------------------------------/
PINOUT NUMBERING:
HP49G-10pin-M HP49G-10pin-F
+-------/-\-------+ +-------/-\-------+
| 1 2 3 4 5 | | 5 4 3 2 1 |
| 6 7 8 9 10 | | 10 9 8 7 6 |
\-----------------/ \-----------------/
PINOUT DESCRIPTION: 6. SHIELD 7. TX (TRANSMITTED = CALCULATOR OUTPUT) 8. RX (RECEIVED = CALCULATOR INPUT) 9. GND
DB9-M DB9-F
------------------- -------------------
\ 1 2 3 4 5 / \ 5 4 3 2 1 /
\ 6 7 8 9 / \ 9 8 7 6 /
--------------- ---------------
PINOUT DESCRIPTION:
2. DATA-IN (COMPUTER INPUT = DATA FROM CALCULATOR)
3. DATA-OUT (COMPUTER OUTPUT = DATA TO CALCULATOR)
5. GND
DB25-M DB25-F
--------------------------- ---------------------------
\ 1 2 3 [..] 11 12 13 / \ 13 12 11 [..] 3 2 1 /
\ 14 15 [..] 23 24 25 / \ 25 24 23 [..] 15 14 /
----------------------- -----------------------
PINOUT DESCRIPTION:
2. DATA-OUT (COMPUTER OUTPUT = DATA TO CALCULATOR)
3. DATA-IN (COMPUTER INPUT = DATA FROM CALCULATOR)
7. GND
PS/2-M PS/2-F
--v-- --v--
/5 | 6\ /6 | 5\
|3 4| |4 3|
\ 1 2 / \ 2 1 /
----- -----
PINOUT DESCRIPTION:
2. DATA-IN (COMPUTER INPUT = DATA FROM CALCULATOR)
6. DATA-OUT (COMPUTER OUTPUT = DATA TO CALCULATOR)
3. GND
To know the pinout assignment used by me, please refer to the previous section.
3.1. Project #1: Recycling an old motherboard connector or a mouse cable.
What you need: a DB9-F connector, some wires and a 10pin-F connector to plug into the HP49G port. Note that in the calculator you only need to connect three pins (since SHIELD is not mandatory), all in the bottom-row (pin 7 to 9); so you can get it by recycling the 3 (or 4)-pin female connector used into old computer mainboards (for example: hdd-led, turbo-led, keylock-switch, etc.), or get it from some broken hardware (for example, the cable of an old mouse). If you're going to recycle a PS/2 mouse cable, please also refer to section 5.2.
Ask to a computer shop or, better, to a surplus-dealer in order to find a computer connector that fits the pins (6),7,8 and 9 in your HP49G.
Building the cable: Solder the 3-pin-F connector to the DB9-F.
Schematic:
HP49-F DB9-F
SHIELD (6)---------------(SHIELD)
TX 7---------------->2 DATA-IN
RX 8<----------------3 DATA-OUT
GND 9-----------------5 GND
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3.2. Project #2: Using the HP38 serial PC-Link cable.
What you need: any HP38-compatible serial cable.
The HP38 has the same pinout of the HP49G. So, you can use safely any HP38 cable in your HP49G (for example, F1207B, 8120-6736 or F1897).
Anyway, check the cable before using it.
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3.3. Project #3: Using the HP49-HP49 cable you get with the calculator.
What you need: The HP49-HP49 serial cable you get with the calculator (part/no. F1633-66000), a DB9-F connector and a DB9-M connector.
Building the cable:
NOTE: the two half are reciprocal (the output of the first is the input of the second and vice-versa).
Schematic:
FIRST HALF SECOND HALF
HP49-F DB9-F HP49-F DB9-M
SHIELD (6)---------------(SHIELD) SHIELD (6)---------------(SHIELD)
TX 7---------------->2 DATA-IN TX 7---------------->3
RX 8<----------------3 DATA-OUT RX 8<----------------2
GND 9-----------------5 GND GND 9-----------------5
Pinout numbering is different (mirrored) in DB9-M and DB9-F connectors! Be careful!
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3.4. Project #4: Using the HP48 serial PC-Link cable.
What you need: a DB9-F connector and the HP48 serial PC-Link cable. In this section (and in the next) I'm referring to old models of cable. Newer models (like F1207B, 8120-6736 or F1897) has an adapter to use them with the HP38. So you can use them safely in your HP49G too. For these newer models, see section 3.2.
Assuming you own an older model (like F1015-80002). This cable was born for the handheld computer HP200LX, then was sold with an adapter (5181-6643) to use it as official HP48 PC-Link.
NEVER (**NEVER**) plug this cable directly in your HP49G. You could damage it!
To use this cable with the 49G, you need to modify the DB9-F pinout (this section) or to build a DB9-DB9 adapter (next section).
Building the cable:
Schematic:
HP49-F DB9-F
SHIELD (6)---------------(SHIELD)
TX 7---------------->2 DATA-IN
RX 8<----------------3 DATA-OUT
GND 9-----------------5 GND
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3.5. Project #5: Using the HP48 PC-Link by building an external adapter.
What you need: some wires, a DB9-M and DB9-F connectors and the HP48 serial PC-Link cable. In this section (and in the previous) I'm referring to old models of cable. Newer models (like F1207B, 8120-6736 or F1897) has an adapter to use them with the HP38. So you can use them safely in your HP49G too. For these newer models, see section 3.2.
Assuming you own an older model (like F1015-80002). This cable was born for the handheld computer HP200LX, then was sold with an adapter (5181-6643) to use it as official HP48 PC-Link.
NEVER (**NEVER**) plug this cable directly in your HP49G. You could damage it!
To use this cable with the 49G, you need to build a DB9-DB9 adapter (this section) or to modify the DB9-F pinout (previous section).
Building the cable:
+-------+ +-----------------+ +----------+ | HP49G |<---------------><--| DB9-DB9 ADAPTER |-->| COMPUTER | +-------+ HP48-PCLINK +-----------------+ +----------+
Schematic of the DB9-DB9 adapter:
DB9-M DB9-F
SHIELD (4)---------------(SHIELD)
TX 8---------------->2 DATA-IN
RX 7<----------------3 DATA-OUT
GND 9-----------------5 GND
Pinout numbering is different (mirrored) in DB9-M and DB9-F connectors! Be careful!
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Before using your new cable for the first time, check it!
What you need: a ohmmeter (or a multimeter or a similar device).
No matter what method you've followed. The cable you use MUST have:
HP49-F DB9-F
SHIELD (6)---------------(SHIELD)
TX 7---------------->2 DATA-IN
RX 8<----------------3 DATA-OUT
GND 9-----------------5 GND
4.1. HP49 RS-232 Loopback Test
To perform the RS-232 Loopback Test:
To CLOSE the RS232 ring, simply shunt PIN 2 & 3 in the DB9-F using a piece of wire or a folded clip.
If you get RS-232 TEST OK in the upper side of the screen, the cable is probably well done.
Otherwise, check the cable. (see previous section).
5. Using different connectors.
If you want to plug the cable to a DB25 serial port, you should modify the projects above in this way:
HP49-F DB25-F
SHIELD (6)---------------(SHIELD)
TX 7---------------->3 DATA-IN
RX 8<----------------2 DATA-OUT
GND 9-----------------7 GND
If you want to recycle a cable with the PS/2 6-pin connector at its end (for example, an old mouse cable), you should modify the projects above in this way:
HP49-F PS/2-M
SHIELD (6)---------------(SHIELD)
TX 7---------------->2 DATA-IN
RX 8<----------------6 DATA-OUT
GND 9-----------------3 GND
Now you need a PS/2 to COM adapter, in order to plug finally the cable in a COM port or your PC.
Don't connect the PS/2 cable directly in the PS/2 port (mouse port): it won't work, and you could damage the motherboard or the calculator itself.
The adapter you must use, should connect at least PIN 2, 3 and 5 on DB9 side, like this: (Schematic taken from Microsoft X03-55560 adapter for Wheel Mouse)
PINOUT ASSIGNMENT:
PS/2-F DB9-F
SHIELD----------------SHIELD
TX 2--------------->2 DATA-IN
RX 6<---------------3 DATA-OUT
- 5----------------4 -
GND 3----------------5 GND
- 5----------------6 -
- 4----------------7 -
(Thanks to Giovanni Casoli for providing this information).
HP49G already includes in ROM the communication software. Read Appendix A of the user's guide or go to http://www.hp.com/calculators/hp49 for more information.
So you only need the software for your computer in order to connect it with the HP49G and transfer files and flash-ROM upgrades.
All the required software is FREE (please read the provided GNU general public license).
These are the most frequent questions I have received. Read carefully before asking for help. If you still cannot solve your problem, feel free to contact me.
Q: Can I use these cables to upgrade the flash-ROM? And where can I get the communication software?
YES, you can use the cable to upgrade the flash-ROM.
For getting software, please read section 6. The required software is available directly from HP, for FREE downloading.
Q: I don't own a ohmmeter. What project could I do?
Sorry, but you need the ohmmeter for each project. If you haven't one, just ask for help to any electronics shop (like Radio Shack).
Q: What is the SHIELD? Should I connect it?
The SHIELD is simply the metallic shell in the outer part of each connector. The shield wire (when present) is the outer conductor you find into the cable after having sliced it.
You can choose both to CONNECT and DON'T CONNECT the shield. Only, don't let it floating near the connector pins !
Q: Texas Instruments calculators cable use a resistor and a diode. Your doesn't. Is it safe?
HP calculators use the standard RS-232 interface. So you don't need to plug any resistor or diode onto the connectors. Just the wires to route all the required pins from the calculator to the PC (as for serial devices like modems or mice).
Q: Could you say the color-code of each wire (i.e., RED wire in pin #7, etc.)?
After sliceing a cable, you'll find a lot of colored wires.
As I have been told, the colour of the wires may vary, and may vary the pin each wire is connected to. You always need an ohmmeter to recognize each wire.
Q: The cable doesn't work. And now?
Q: I've checked the cable, so I'm pretty sure it works; but I cannot use the HPComm software. What should I do?
Q: What is the preferred Project?
As I'm told, the Project #1 using a mouse cable. Followed by #3. But if you already own the old HP48 PC-Link, the best choice is Project #5 (what I currently use).
Q: Are you developing a Macintosh version of this page?
Sorry, not at this time.
9. Obtaining the last version of this document.
Primary address for this page is: http://www.geocities.ws/hpcables/cable49g.htm
Secondary address: http://studenti.ing.unipi.it/~s172776/cable49g.htm
PK-zipped version: (14 Kb) http://www.geocities.ws/hpcables/cable49g.zip
Text-Only version: http://www.geocities.ws/hpcables/cable49g.txt
10. Contacting the author of this document.
Feel free to contact me for any problem or question.
My E-mail addresses are:
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