CHAPTER
1
I
NTRODUCTION
ALR-9680
H
ARDWARE
S
ETUP
G
UIDE
DOC.
CONTROL
#8102135-000
REV
A
5
I/O Port Terminal Interface
The ALR-9680 I/O port provides two digital inputs, two digital outputs and a
ground return. The design provides protection against momentary over and
reverse voltage application to the inputs or outputs and short circuit of the
outputs. The inputs and outputs are TTL compatible. When set high, outputs will
sink ~1 mA with 5 volts applied.
Caution: The absolute maximum voltage applied to any input or output shall not
exceed 5.5 volts.
I/O Recommended Operating Conditions
Inputs
Logic “0”
0 – 0.8 VDC
Logic “1”
2.0 – 5.25 VDC
Outputs
I
source
20 mA @ 3 VDC
I
sink
20 mA @ 0.5 VDC
Unlike the Alien enterprise readers (ALR-9800 and ALR-9900+) the
ALR-9680 I/O’s are not optically isolated. Instead they are buffered internally. As
a result the outputs can source up to 20 mA’s without the external supply
required for the enterprise Readers. Outputs should be protected from transients
such as inductive kickback so as to not exceed the absolute maximum voltage
allowed at the outputs. The circuit diagram below illustrates the input and output
equivalent circuits.
Figure 2 - Input and Output Circuits
ALR-9680
Pin 5
Pins 3, 4
Pins 1, 2
Terminal
Block
