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The victim resting in its natural habitat. |
My mother wanted to be able to update some of the stitches on her PFAFF 1475CD using her PC. As the process of programming on the machine itself is tedious and does not lend it self to corrections. I had two problems to solve off the bat. First the cable is a D-Sub 25pin Serial RS232. No computer in the last 20 years has been made with this connector.
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"Made for PFAFF in West Germany" |
I had a DB25 to DB9 adapter, but modern computers, laptops even more so, don't have 9 pin serial ports... So i grab a USB to serial adapter. Unfortunately the manufacture, Prolific, intentionally didn't support Windows 7 or 10. bummer.
I found in an old "Random Electronics Junk Box" a Keyspan serial adapter. Great! the Drivers work with Windows 10, ComPort33. OK but what about the software?
The software is from 1990. Meaning MSDOS. Well i happen to be a vintage video game enthusiast and run many old dos games using the wonderful DOSBOX program. But could it handle a physical serial port? The manual, you guys/gals read the manual don't you? The manual says YES!
Cool! so following some configuration and more near swearing than I'd like to admit...
I was able to read to contents of the machine's memory using the PFAFF Creative Designer software from within DOSBOX using the many adapters to talk to the machine. The solutions was ugly and unwieldy. It risked being broken.
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Big ugly complex fragile cable. |
So I searched for a better solution. Enter Limor "Ladyada" Fried and her crew at Adafruit Industries. They make a cable that will work perfectly for this application and it's low cost. USB to TTL Serial Cable.
All I need now is a connector for the PFAFF 1475CD machine, a 7pin DIN. Thanks Amazon! http://amzn.com/B07XCSX3JP
With a two part count and my soldering iron I'm ready to improve the situation!
Now for a bit more background and the technical details of how I pulled it off:
The original PFAFF cable (made in West Germany by the way) was a DB25 to 7 pin DIN connector. Inside the D shaped 25pin connector (DB25) is a circuit, depicted far below, that converts and inverts RS232, 25 Volt Direct Current differential signal to 5vdc TTL signal. PFAFF used a 5vdc supply from the machine to power and reference this circuit. We won't need the circuit as the TTL-USB adapter makes the circuit unnecessary.
We won't be using PFAFF +5v supply and will leave the pin unconnected. The TTL-USB adapter has a +5v supply as well. I used heat shrink to cap it off safely as we won't be using it either.
Red +5vdc -/- no connection
PFAFF +5vdc DIN7 Pin 3 -/- no connection
Now we connect a common signal reference and grounding wire (GND, black, to pin 4 on the DIN7 connector).
Black gnd -- DIN pin 4
Connect the TTL-USB Transmit to PFAFF receive and vise versa:
Green tx -> DIN pin 1
White rx <- DIN pin 7
Adafruit TTL-USB -- DIN7 connector summary:
Green tx -> DIN pin 1
Green tx -> DIN pin 1
White rx <- DIN pin 7
Black gnd -- DIN pin 4
Red +5vdc -/- no connection
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My USB-TTL to DIN7 pin out |
Ok, I know my soldering isn't pretty in these images. I did it quick. After testing and confirming everything works, I redid this and used matching color heat shrink.
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TTL adapter soldered to DIN7 connector |
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Inside the adafruit USB-TTL adaptor |
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Rudolf's pinout diagram of the PFAFF serial cable. |
PC TX serial pin 3 -> brown PFAFF RX (pin 1)
PC RX serial pin 2 <- yellow PFAFF TX (pin 7)
Ground serial pin 7 -- green gnd (pin 4)
No connection* -/- white vcc (pin 3)
Ground serial pin 7 -- green gnd (pin 4)
No connection* -/- white vcc (pin 3)
*while the PFAFF white (DIN7 pin3) does not have a pinout on the DB25, it does supply power and a voltage reference to the circuit housed in the DB25 connector.
This circuit converts and inverts RS232 signal to TTL signal.
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Rudolf's circuit diagram of the original PFAFF serial cable. |
DOSBOX conf (windows, you may have to adjust the com-port number):
serial1=directserial realport:COM33
DOSBOX conf (linux/mac, you may have to adjust the USB tty number):
serial1=directserial realport:ttyUSB
DOSBOX conf (all systems)
[autoexec]
#mount c ~/dos/PFAFF
mount c c:\users\USER\PFAFF\
C:
PCD.EXE
exit
Thanks to:
C:
PCD.EXE
exit
for the software create a PFAFF directory (case sensitive) and copy the PCD program files to it. adjust the [autoexec] section of dosbox.conf to mount the PFAFF directory. upon running dosbox the PCD program should automatically launch.
Parts:
Software: