Dot matrix printer connected to a legacy data-logger, which monitors data from hundreds of critical valves and switches. The dot matrix printer was also beat up, and had problems like paper jams and sometimes ink would not be replaced timely. This resulted in loss of information from the data logger.
The parallel port(centronics) of the datalogger connected to arduino , data is read on the atmega8 port and sent to serial output. On the PC, a python script logs the data into a text file, new file is created everyday and new folders are created every month for easy access. The python scripts also monitors if it looses connectivity, it can be reconnected and the logging would start without restarting the script. The data is very critical and they don't mind running a PC 24x7. I used a custom made arduino running atmega8 with CP2102 usb to TTL. The system was turn-on in July 2014 and going strong.
I made this project in two phases.
1. I wrote a small program on arduino to talk to the printer.
2. Replace the printer and interpret data from the data logger.
Sadly, I don't have any photographs, of it in action as photography is prohibited on their premises.