This started because my mother wanted to update some stitches on her **PFAFF 1475CD** from a PC. Programming directly on the machine works, but it is slow and unpleasant if you need to make corrections.
The first problem was physical connectivity. The original cable is **DB25 serial to 7-pin DIN**, which is not exactly friendly to modern computers.
The victim resting in its natural habitat.“Made for PFAFF in West Germany.”
I had a **DB25 to DB9** adapter, but of course that only solved part of the problem. Modern PCs, and especially laptops, generally do not have a 9-pin serial port either.
I first tried a USB-to-serial adapter based on a Prolific chipset. That turned into its own headache because of driver support.
DB25/DB9 adapter.
Eventually I dug up an old **Keyspan** USB serial adapter from the random electronics junk box. That worked under Windows 10 and showed up as **COM33**.
Keyspan serial USB adapter.
The software side was even more fun. The original PFAFF software is from the DOS era, so the obvious question was whether **DOSBox** could talk to a real serial port. Fortunately, the answer is yes.
I eventually got the Creative Designer software talking to the machine through DOSBox, but the adapter stack was ugly, fragile, and annoying.
Big ugly complex fragile cable.
So I went looking for a cleaner solution. The better answer turned out to be a **USB-to-TTL serial cable** from Adafruit plus a **7-pin DIN connector** for the sewing machine.
A much cleaner and more elegant solution.PC-Designer Software v1.3 running in DOSBox.
## How it works
The original PFAFF cable is not just a passive cable. Inside the DB25 shell is a circuit that converts and inverts **RS232** signaling into **5 V TTL** signaling.
Because the Adafruit cable already handles the USB-to-TTL side, that conversion hardware is no longer needed.
The machine also provides a **+5 V** line on the DIN connector for the original interface electronics. I did **not** use that line here, and I also left the USB adapter’s own +5 V line disconnected.
## Wiring
Red +5Vdc -/- no connection
PFAFF +5Vdc DIN7 pin 3 -/- no connection
Black GND --> DIN pin 4
Green TX --> DIN pin 1
White RX <-- DIN pin 7
### Summary
Adafruit USB-TTL -> PFAFF DIN7
Green TX -> DIN pin 1
White RX <- DIN pin 7
Black GND --> DIN pin 4
Red +5Vdc -/- no connection
My USB-TTL to DIN7 pinout.
I will freely admit the soldering in these photos was not pretty. I did it quickly to prove the wiring, then redid it more cleanly afterward with matching heat shrink.
TTL adapter soldered to the DIN7 connector.Another view of the DIN7 soldering.Inside the Adafruit USB-TTL adapter.
## Original cable details
Rudolf at [achatina.de](http://www.achatina.de/sewing/INDEX.HTM) documented the original PFAFF serial cable well, including both the pinout and the interface circuit inside the DB25 connector.
Rudolf’s pinout diagram of the original PFAFF serial cable.
Original RS232 (DB9/DB25) -> PFAFF 7-pin DIN
PC TX serial pin 3 -> brown PFAFF RX (DIN pin 1)
PC RX serial pin 2 <- yellow PFAFF TX (DIN pin 7)
Ground serial pin 7 --> green GND (DIN pin 4)
No connection -/- white VCC (DIN pin 3)
The white PFAFF wire on **DIN pin 3** does not map through as a normal signal line on the DB25 side, but it does provide power and a reference for the interface circuitry inside the original cable shell.
Rudolf’s circuit diagram of the original PFAFF serial cable.
## DOSBox configuration
### Windows
serial1=directserial realport:COM33
### Linux or macOS
serial1=directserial realport:ttyUSB
### DOSBox autoexec example
[autoexec]
# mount c ~/dos/PFAFF
mount c c:\users\USER\PFAFF\
C:
PCD.EXE
exit
Create a `PFAFF` directory, copy the program files into it, and adjust the `autoexec` section of `dosbox.conf` so DOSBox mounts that directory and launches the program automatically.
## Parts
- [Adafruit USB to TTL Serial Cable](https://www.adafruit.com/product/954)
- [7-pin DIN connector](http://amzn.com/B07XCSX3JP)
## Software
- [PFAFF software archive](https://drive.google.com/file/d/1tudIsC2i-2bd5y_QcJR5lMiZx0dHVXgm)
- [DOSBox](https://www.dosbox.com)
## Thanks
- [achatina.de](http://www.achatina.de/sewing/INDEX.HTM)
- [milnerwm archive](http://users.cyberport.net/~milnerwm/)
- [Adafruit](https://www.adafruit.com/about)
- [DOSBox manual — serial support](https://www.dosbox.com/DOSBoxManual.html#Multiplayer)
- [Additional reference](http://members.ziggo.nl/rwfvandersluis/blog/files/84bf36eb9d6e848e67d8a7d5b67cc116-4.html)
- [PatternReview discussion](https://sewing.patternreview.com/SewingDiscussions/topic/95197)
