CHAPTER
4
IF1C
Fixed RFID Reader User Guide
29
GPIO PORTS
GPIO Interfaces
The reader has two general purpose input and output (GPIO) interfaces. You con-
nect external controls such as motion sensors or indicator lamps to the GPIO inter-
faces, which can then trigger reader operations.
Each interface is electrically isolated from the reader and designed for low voltage
DC loads. The reader can also supply 5Vdc at 0.30 A to external devices.
The
output interfaces (GPO1, GPO2)
interfaces are limited to a maximum of
150mWatts.
How the inputs and outputs are used depends on the RFID application software
being used in the system. You need to coordinate input and output control wiring
with the software developer.
Input Interfaces
Each of the two inputs is compatible with input signals of 4.5 to 28Vdc. Both the
high and low signal contacts are exposed and isolated to 1500V. Input
impedance is 1.8K ohms minimum.
In a typical application, the reader senses input from an external control like a
switch and then starts a tag read operation.
There are three basic ways to connect input controls to the reader input interfaces:
•
Supply the input interface with power from the reader
•
Isolate the reader from the input power source.
•
Use an open collector solid state drive from a remote device to control the
inputs.
Signal
Description
Min.
Typical
Max.
V
in
(High)
High input voltage
4.5V
24V
28V
V
in
(Low)
Low input voltage
-1V
0V
.8V
