Hi, Actually, I built exactly this many years ago (1990s) to operate a cash draw for dumb terminals on Unix systems, used on counters as point of sale devices...
The existing solution used a processor, ram, rom, double sided board etc and was too expensive, so I designed a replacement with a real UART and a finite state machine consisting of a EPROM and 8 bit latch that simply monitored the RS232 data passively and when the appropriate character sequence was matched, it triggered the solenoid to open the cash draw. It decoded a long 14 character code sequence easily and reliably and used 5 chips in total on a smaller single sided board. Nowadays, a small microcontroller is the obvious way to go for cost and ease of development. An easy way to implements is to use a small box to contain the two DB25 connectors and simply tap into the receive data line and run a short cable to the monitor circuit, probably built in and powered off what you want to operate... Regards, Robin Downs -----Original Message----- From: W2HX via cctalk <cctalk@classiccmp.org> Sent: 11 November 2022 21:16 To: General Discussion: On-Topic and Off-Topic Posts <cctalk@classiccmp.org> Cc: W2HX <w...@w2hx.com> Subject: [cctalk] Inline Serial Device? Hello all, I am looking for a device that sits transparently in an RS-232 serial line and upon seeing a particular code go over the serial line ((or sequence of codes) will actual a relay (or a transistor). Something with two DB25s or DE9s and is configurable to what code will trigger the output? Some kind of box? Does anyone know of such a thing? I guess it could be cobbled up with a microcontroller, but hoping to just get something "off the shelf." Thank you 73 Eugene W2HX Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx
