IF1C
Fixed RFID Reader User Guide
31
Open Collector Input Interface
Each reader output interface is optically isolated from the reader, polarized, and
rated 5 to 24VDC at 5mA
.
Because the outputs are optically isolated, each one can be configured 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.
In a typical application, the outputs control indicator lamps that signal good reads
or errors. The basic methods for connecting external devices to the GPIO outputs
include:
•
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
•
Driving a DC relay that controls an AC load
These methods are shown in the following examples.
Switch the High Side with Reader Power
In this example, an external indicator lamp (0.25A maximum current) is connected
to the -Output and Ground pins, and the correspOutput pin is connected
to the +
5
V
dC
source.
+Input
+5 V
Ground
- Input
Signal
Description
Min.
Typic
al
Max.
Leakage
current
(High)
Switch output, high leakage current
0mA
1mA
10mA
V
sat
(Low)
Switch output on, saturation voltage with
5mA
maximum current
0
V
1V
1.5V
Output Interfaces
