Revision 3.1
WebRelay
TM
Users Manual
pushbutton, or users can operate the gate from another room using a web browser. Another option (not
shown here), is to connect another pushbutton switch to the input of a second WebRelay
TM
device in a
room across the building. The second device could be configured to send control messages to the first
device each time the new pushbutton is pressed. As a result, there is a second pushbutton that could
operate the gate.
2.2.4 Optically-Isolated Input Connection
The optically-isolated input can be used to control the relay, control a remote relay, or simply to monitor a
discrete device. To use this input, connect a DC signal voltage directly to the control input. A current
limiting resistor is provided internally, so no external resistor is required (unless the signal voltage is greater
than the maximum input voltage rating). If an AC signal, or a signal greater than the rated input voltage
needs to be connected to WebRelay
TM
, use a signal conditioner to convert the signal to the proper voltage.
Signal conditioners can be made of discrete components or can be purchased at industrial automation
distributors.
To connect an AC voltage to the input of WebRelay
TM
, a diode (or bridge rectifier) and a capacitor can be
used to convert the AC signal to a DC signal. To connect a voltage to the input of WebRelay
TM
that is
greater than the input is rated, a resistor of the appropriate value and power rating can be used to reduce the
voltage.
The formulas to calculate external resistor values is provided below
For ControlByWeb
TM
products with a 3-12VDC input range...
R = (V-9)/0.020
V = Desired Vin
R = External resistor value required. The external resistor must also be rated with a minimum power value
(minWatts=(V-9)x0.020)
For ControlByWeb
TM
products with a 11-28VDC input range...
R = (V-28)/0.014
V = Desired Vin
R = External resistor value required. The external resistor must also be rated with a minimum power value
(minWatts=(V-28)x0.014)
Xytronix Research & Design, Inc.
page 16
WebRelay
COM
NO
Device to Control
Existing pushbutton switch that
performs desired function
Device
Circuitry
WebRelay contacts are connected in
parallel to existing switch.