Matrox 4Sight EV6 Installation And Hardware Reference page 41

Bleeder resistor
Equivalent circuit only
About the
connections in the
following
subsections
By default, if properly configured, the current should flow from the AUX_INn+
pin (connected to a sourcing device) to the AUX_INn- pin, unless the connected
output device closes the circuit. In some cases, the amount of current going
through the sensing circuit is insufficient for the connected output device to match
its minimum current requirement when the device is in an on or off-state,
depending on the configuration of the circuit (for example, 2-wire proximity
sensor). To boost the flowing current, connect a 2.2 KOhm external bleeder
resistor between the AUX_INn+ and AUX_INn- pins. For example:
Sensing
Circuit
The following subsections detail how to connect the most common third-party
devices to the Matrox 4Sight EV6 auxiliary input signals.
Note that ground is only shown in the following subsections for reference, in case
you need to reference your return path to ground for some other reason (for
example, if you want to reference your return path to the chassis's ground).
Power, as depicted in the following diagrams, represents a nominal voltage of 24 V
(+/- 10%). For minimum and maximum voltage requirements, refer to the
electrical specification of the electrically-isolated auxiliary input signals, in the
Matrox 4Sight EV6 electrical specifications section, of Appendix B: Technical
reference.
Connecting to the auxiliary I/O interface
AUX INn+ _
AUX INn- _
External
Bleeder
Resistor
41