activate the input. Devices such as open collector drivers or any
device capable of sinking at least 1 ma can be used to drive
discrete inputs. Never connect any signals that exceed the 5 Volt
operational voltage of the KE24.
Figure 1.2 is an example of connecting an input to the KE24
when the I/O pins have been
configured for matrix operation.
One I/O pin defined as column
is shorted to one I/O pin
defined as a row. In this mode,
the switch or input device must
be capable of carrying at least
1 ma. Typically, the device used
for activating inputs in this mode
are keypads or switches, but
other electronic circuits may
be used, provided they do not
exceed the 5 volt range of the
KE24 I/O. Pins defined as Rows
in this mode sink current while
scanning, and the Columns are
used to read the status of the
inputs when a column is active.
There are two DIN type connectors located on your KE24. Although
the connectors are physically alike, they have different functions.
The connector marked “To PC” is for interface of the KE24 to the
computer’s keyboard input. Insert one end of the 5 pin DIN (male
to male) shielded cable into this port. Connect the other end of
the cable into your computer’s keyboard input. Always perform
this connection with the computer’s power off.
The connector marked “KBD” is for using an external keyboard
6
Figure 1.2
In matrix mode,
inputs are acti-
vated by short-
ing a pin defined
as a row to a pin
defined as a col-
umn.
Column
Column
Row
(open)
(closed)
Appendix A:
KE24 Specifi cations
Operating Voltage
5 Volts DC +/- 5%
Operating Current
65 ma Typical
Operating Temp.
0 to 70 degrees C
PC Interface
XT or AT PC Compatible (5 pin
DIN)
Keyboard Interface
XT or AT Compatible (5 pin DIN)
Serial Port
RS-232, 300 Baud to 19,200
(8, N, 1)
I/O Header
24 I/O, up to 12x12 Matrix
(programmable)
Req. Input Current
1 ma of sink current in for discrete
inputs
25
3.0”
Note: Maximum Height = .91
.125 Dia. (4)
.150
.150
4.0”
