Proximity sensors-tell me if I'm wrong


I have 2 plasma torch collision sensors that act like transistors. Am I correct to assume that I would hook these up to inputs just like homing sensors, which would in turn activate a masso relay? Thanks!


@m1088 - Does the transistor switch to ground (NPN type) or switch to positive rail (PNP type)?

If the transistor switches to the positive rail (PNP type) you should be able to drive both a MASSO G3 controller input and a MASSO Relay input simultaneously from the same sensor output.

If the transistor switches to ground (NPN type) then you will require a pull-up resistor. For purposes of sizing the pull-up resistor assume that the MASSO G3 controller input and the Relay Input both require 1 mA each @ 5V. If you are using a 24V power supply then the resistor needs to be (24V - 5V) / (2 x 0.001 A) = 9500? (use a 8.2K resistor).

The 1 mA @ 5V to trigger an input is a conservative number, the actual trigger voltage / current is closer to 0.5 mA @ 3.5V.


Staff member
Hi M1088

MASSO has an input for torch breakaway if you want to use that.

Cheers Peter