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OMREX
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ORPORATION
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STAC Product Manual
15
The STAC mainframe provides status indications via the DB-25 parallel
port on the rear panel. This is essentially a computer printer port, so it is
only capable of sending TTL level status signals and cannot source or sink
significant current. An accessory box is available to convert these signals to
relay-based contact closures, capable of switching high voltages and cur-
rents directly.
The interface box we tested is model CK1621 available from Carl’s Elec-
tronics at
http://www.electronickits.com - +1 978-422-5142
. This device
provides normally-open and normally-closed contacts for each of the eight
signals available on the parallel port.
Note: The CK1621 is not supplied with a 12V power supply or straight-
through DB-25 cable, both of which are available at electronic retailers
like Radio Shack.
At this time, two signals are available on the parallel port of the STAC main-
frame (using firmware 1.2 or higher):
Table 3 - Parallel Port Pinout
Pin #
Name
Description
2
Line Ringing
(Active High)
Goes Active when any line is R
inging
3
Record Trigger
(Active High)
Goes Active when any line is put
On Air
Ground is available on Pins 18-25 of this connector.
STAC M
AINFRAME
S
TATUS
I
NDICATIONS
