#54, M1S: Four Dry Contact Inputs

Function: Four dry contact inputs; external switches should be installed between the input terminals and the system ground.

Form factor: M1S

Category: Input module

Special needs: ---

Power requirements: 5V/40mA

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

See also: #04-1, #04-2, #04-3, #04-4, #04-05, #04-06, #04-07, #04-08

Details

Unlike Tibbit #04, this device requires no external power to control its inputs: Shorting an input to the system ground will activate this input and set the corresponding control line LOW.

Note that these are not "isolated inputs," even though they feature opto-couplers in their circuitry. Still, the optical stage isolates your system from noise, electrostatic discharge (ESD), spikes, and other external disturbances.

Combine this Tibbit with terminal block devices — #20 (nine terminal blocks) or #21 (four terminal blocks). Note that this Tibbit does not provide a ground line, so you will need to "steal" the ground elsewhere. The ground is immediately available on terminal 5 of Tibbit #20.

LEDs

There are four green LEDs connected to the four control lines. An LED lights up for the LOW state of a control line (i.e., when the corresponding input is shorted to the system ground).