Take the 2-minute tour ×

My aunt bought this cash drawer at an auction recently and has tasked me with figuring how to open it via a computer. We have the key (pictured) and can open it manually, but I'd like to be able to plug it directly into a computer and open it via some sort of program or script. It has a built in rj-11 cord coming out of the back of it. Initial research shows that it might usually be used with a printer, but I want to be able to connect it directly to the computer.

Edit: this needs to be able to work with windows 7.

Edit2: http://imgur.com/a/czEMs imgur gallery of the innards.

enter image description here

enter image description here

share|improve this question
OOH, really obscure bit of hardware. I'd probably warn that not all 'RJ11' connectors are actually RJ11 - it might be a similar jack with a different pinout. –  Journeyman Geek Nov 22 '11 at 5:12
Can you open it enough to see where the pins go? It might be a simple switch, so you'd just need to connect ground and one of the other wires to trigger an open. –  Paul Nov 22 '11 at 5:18
This looks exactly like my M&H Cash Drawer, which came with a serial connector. I used it from 1988-1995 and it was connected to the COM port of my DOS computer running Micro Register software. Micro Register is still available for Windows. The software knew how to open the drawer. –  user149520 Aug 1 '12 at 2:38
add comment

4 Answers

up vote 2 down vote accepted

Like Journeyman Geek said: "Not a definitive answer" but all the older cash drawers where I used to work (30 customer outlets) connected to a serial port via an RJ11-Serial lead and sending pretty much any string of characters to the port at around 300-1200 bps would trigger the cash drawer to open. The newer ones were driven directly from a USB port.

We had an 'emergency open' icon hidden away on the reception PCs and it linked to a batch file that contained a mode line to set the com port parameters and then something like "ECHO AAAAAA > COM1:"

For the POS application, the cash drawer was defined as a serial-based printer and the app would 'print' a short line of text to the drawer to open it.

We had a couple of VERY old cash drawers that had an interface box plugged in to the serial port and onwards to the drawers, but most of the ones we had used direct serial port connections.

share|improve this answer
in my case, its not a definitive answer cause i don't actually know anything about them - i made a lot of educated guesses ;p –  Journeyman Geek Nov 28 '11 at 14:26
add comment

Not a definitive answer, but a quick bit of googling suggests a few things. Mainly, in short, you can't, not with a standard port of any sort from a standard PC without a suitable printer thats part of a POS system.

Firstly, that these drawers connected to printers in some manner, and the pinout depended on the printer (see this and this, and without a suitable printer, this may not be doable at all.

However, apparently they are fairly simple devices - the printer would trigger a solenoid that would open it, its device independant other than the cable, as such either a standard interface, or something very simple, and these use 12V. You might be able to get the drawer connected to a RS232/Serial connector if you have one, since the voltage levels appear to be within spec but some testing might be needed. If this fails there's no simple way to get a 12 V signal out of a system, so you would likely have to work out how to trigger the device, possibly using voltage off the power supply of the system, some kind of relay, and possibly a microcontroller - the exact process would be far out of the scope for SU.

I'd recommend finding the pin out on the cash drawer side, and proceeding from there.

share|improve this answer
add comment

This drawer by itself cannot be connected to the computer directly. You may have to contact MMF, or make your own wiring and controls for it.

share|improve this answer
add comment

This cash drawer connect to a computer via a Star or Epson 40 column receipt printer. You connect the printer through a parallel port.

That is actual a RJ12 cable. It plugs into a RJ12 port on the recceipt printer.

You send a special (hidden) character to the printer. When the printer sees the special character, it pops open the drawer.

share|improve this answer
add comment

Your Answer


