Crystal Vision
Hardware installation
TANDEM HD-20 User Manual R1.4
13
24/05/2007
2.4 General Purpose Interface (GPI)
Each frame slot has up to six connections ‘a-f’ for GPI control and monitoring. These
connections are available at the rear of the frame on the 26-way D-Type remote connectors.
GPI
Low (<1V)
High (+5V)
0
‘a’
Recall preset bit 1
1
‘b’
Recall preset bit 2
2
‘c’
Recall preset bit 4
3
‘d’
Recall preset bit 8
See following table for user preset control
4
‘e’
Video missing
Selected Alarms
asserted
No alarm
5
‘f’
Output channel
silence
(delayed alarm)
Selected Alarms
asserted after set delay
No alarm
As supplied, each GPI output has a 270
Ω
resistor in series with its output. This allows for an
external LED to be driven, connected to a DC voltage of +5V.
Each General Purpose Input (GPI) is fitted with a 6800
Ω
resistor connected to the internal
+5V.
The 16 user preset configurations can be recalled using binary notation.
GPI
Bit 4
Bit 3
Bit 2
Bit 1
Preset
0
0 0 0 0
1
0 0 0 1
2
0 0 1 0
3
0 0 1 1
4
0 1 0 0
5
0 1 0 1
6
0 1 1 0
7
0 1 1 1
8
1 0 0 0
9
1 0 0 1
10
1 0 1 0
11
1 0 1 1
12
1 1 0 0
13
1 1 0 1
14
1 1 1 0
15
1 1 1 1
