WebRelay Users Manual
2.4 Digital Input Connections
The digital input can be used to control the internal relay, control a remote relay (over the network), or
simply to monitor the state of a discrete device. To use this input, connect a DC control voltage directly
to the
Input+
and
Input-
terminals, and set up the function of the input using the configuration pages. A
current limiting resistor is provided internally, so no external resistors are required as long as the
maximum input voltage is not exceeded. If an AC signal, or a signal greater than the rated input voltage
needs to be detected by the WebRelay, use a signal conditioner to convert the signal to a DC signal
within the input range.
2.4.1 Switch-Closure Connections
The WebRelay can sense the state of a switch-closure sensor. Sensors with switch-closure outputs
include push buttons, magnetic door alarm switches, micro-switches, or any device which has a relay,
switch closure, or open collector output. The WebRelay can be configured for the alarm to be active
when the switch is either open or closed.
The illustration below shows an example of using the WebRelay to monitor the status of a gate or door
over an IP network. The status of the device is detected with a switch. These types of sensors are called
“dry contacts” in that the sensor output is a bare switch with no power source. In this example the
voltage source for the switch is provided via the +5V output. When using the +5V output for excitation, a
connection is needed between Input- and GND since the input circuit is isolated.
Xytronix Research & Design, Inc.
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