One of my first jobs was working with devices that emulated paper tape via a serial connection to talk to CNC machines that had a device installed into the old

One of my first jobs was working with devices that emulated paper tape via a serial connection to talk to CNC machines that had a device installed into the old papertape reader to give it a serial port instead. G-Code was loaded by one of the old terminal emulator serial connect software (Procomm? Telix? I can't recall) via a cheap old PC and modem. The machine didn't know it wasn't paper tape. They will probably need to hack up something along the same lines to pretend to be a card printer/reader. Sounds like a job for a Raspberry Pi or similar.