Clear-Com LMC-64 - Manual (Page 103)

Clear-Com
Eclipse Median Instruction Manual 7 - 1 7
Figure 7-9: Wiring the Matrix DB-9M to a DB-25F Computer Serial Port
Connector
WIRING TO AN EXTERNAL ALARM
The DB-9F connector labeled “Alarm I/O” connects the matrix to a
control circuit for an external alarm, such as a light or bell. The external
alarm activates whenever an alarm condition is detected in the matrix.
The following conditions trigger an alarm:
1. If any of the voltages produced by the first power supply unit fall
below their normal levels.
2. If any of the voltages produced by the second power supply unit fall
below their normal levels.
3. If an external alarm circuit or other logic circuit connected to the
power supply is activated.
4. If either of the two power-supply unit fans stop operating.
5. If software on a master CPU card generates an alarm.
An alarm condition activates the relay contacts connected to pins 4, 5,
and 9. These contacts are “dry,” (no voltage is supplied to them by the
matrix) and are rated at 1 A at 24 VDC. They should not be used for
AC mains line current.
Pins are provided for adding an additional alarm source to the matrix’s
alarm system. Pin 6 is an alarm input to the Eclipse Median matrix. It is
connected to the input of a 3.3 V logic device. A logic high on this input
1
2
20
19
18
17
16
15
14
8
7
6
5
4
3
21
11
22
12
23
10
9
25
24
13
1
2
9
8
7
6
5
4
3
Ground (GND)
Transmit (TXD)
Receive (RXD)
Receive (RXD)
Transmit (TXD)
Eclipse Frame
IBM-PC RS-232
DB-9M cable
connector
Computer serial port
DB-25F cable
connector
3