#11, M1S: Four Open Collector Outputs

A purple M1S Tibbit.

Function: Four open collector outputs

Form factor: M1S

Category: Output module

Special needs: [SER] (if reader emulation is desired)

Power requirements: 5V/50mA

Mates with: #19, #20, #21 (limited use)

See also: #16


This module's transistors are rated for a maximum voltage of 24V and a maximum per-channel current of 0.5A. Note that the maximum current should not be exceeded even at lower voltages. Do not apply negative voltage!

To open a transistor, set the corresponding control line LOW. When left unconnected, the control lines default to HIGH (and, hence, the transistors will be closed).

Combine Tibbit #11 with terminal block devices — #20 (nine terminal blocks) or #21 (four terminal blocks). Note that #21 doesn't provide the ground line, and using this Tibbit requires the ground line between the outside world and your system. Hence, if you use Tibbit #21, you will need to "steal" the ground somewhere else.

Another possible use of this Tibbit is emulating clock/data or Wiegand card readers. Our programmable devices (such as the TPP2 and TPP3) have the unique ability to output data in the clock/data or Wiegand formats. This is achieved through the ser. object running in the clock/data or Wiegand mode. Card readers usually have open collector outputs, so this Tibbit is ideally suited as the hardware front end for the job. For this to work, the Tibbit has to be connected to the TX and RTS lines of the CPU's UART (see [SER]).

As with many "real" readers, the equipment on the receiving end will need pull-up resistors.


There are four red LEDs connected to the four control lines. All LEDs are buffered (using logic gates) and light up for the LOW state of the control lines (i.e., when the transistors are in the opened state).

#11, M1S: Four Open Collector Outputs