18 GPIO Terminal Block User’s Guide
Because the outputs are optically isolated, you can configure each one
to switch the high side or the low side of the load. You can power the
load directly from the reader or from an external power supply.
The next examples illustrate several ways to connect controls to the
output terminals:
• Switching the high side, with the load powered by the reader.
• Switching the low side, with the load powered by the reader.
• Switching the high side, with the load powered externally. If the
load being switched requires more than 6 W, you need to provide
external power.
• Driving a DC relay that controls an AC load.
Switching the High Side Using Reader Power
The terminal block is factory configured for high side switching, with
power coming from the reader. Only the single output being switched
is affected if the interface cable fails. This configuration supports
many indicator lamp applications.
By default, the LED indicator for each output terminal is wired in
parallel with the output load, giving visual feedback to users when the
output from the reader has changed state.
Each output terminal includes a jumper that shorts the +12 V and
+Output posts. Connect the output load to the -Output and Ground
posts as seen in the next illustration.
Switching the High Side
Input
Ground
12 V
Reader interface
500 mA max.
External
indicator lamp
0.25 A maximum
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