I have a Star CB2002LC-FN cash drawer. Normally, to kick it, it needs to be connected to the peripheral port of a receipt printer via RJ11/RJ12. The PC can then send a control signal to the receipt printer, which then in turn signals the cash drawer to kick. I believe this protocol is called DKD.

My objective is to mimic this behavior, but without the receipt printer and instead controlling it via our own software.

The solution I came up with was to use an RJ12 to Serial adapter to connect the drawer to PC and trying to trigger it by activating certain pins. I've tried several pin configurations based on different documents I've found online but have not been successful in getting any kind of response from the drawer.

The general idea seems to be that voltage should be provided to two of the pins. By then cutting the voltage to one of the pins the electromagnet (solenoid) should release. I've tried using the serial DTR and RTS pins as I can activate those individually. It might be a simple case of the PC's serial port not providing sufficient voltage.

There seem to be commercial products available that can do this, but I would prefer to DIY a solution if possible.

Is there any way I can accomplish my goal?


1 Answer 1


It does require more voltage. This PDF gives a schematic, albeit for a different model but also using RJ11:

enter image description here

It requires 24V for a few hundred ms, at least 1A.

See also this Epson control PDF. That has the solenoid on pins 4/5, which I think is more common than 2/3.

You should be able to find the solenoid by identifying the pair of pins with a small non-zero resistance. You don't "apply voltage then cut it", you need to supply a pulse through a transistor or suchlike. You could probably control the transistor through DTR.

  • \$\begingroup\$ Thank you for the information. Your answer makes a lot of sense - unfortunately it is a bit too far out of scope for what we're doing. \$\endgroup\$ Aug 10, 2016 at 7:46

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