Contact Wiring
On the optional Contact Modules, switch contacts are wired between the Input pin number and a ground
located on either end of the connector. The inputs are optically isolated using optocouplers. The cathodes of
the LEDs in the optocouplers are connected to the Input connector port pins. The Anodes of the LEDs in the
optocouplers are connected to an internal 12VDC power supply, with a 680 ohm current limiting resistor in
series. The output transistor of each optocoupler has a 10K pullup resistor on its collector, with the emitter
connected to ground and is buffered by an inverting gate. The following diagram is representative of one
input:
INPUTx
GROUND
+12v
+5v
680
ohm
10K
ohm
An input is activated by sinking current from the corresponding input pin to ground. A Ground
connection is supplied on pins 1 and 10 of each Input connector for this purpose. The input current sink
requirement is approximately 15 mA.
Switches may be one of two forms: Normally Open (N.O.) or Normally Closed (N.C.). Switches that are
Normally Open have no electrical connection between the switch terminals unless the switch is activated
closed. Switches that are Normally Closed have an electrical connection between the switch terminals unless
the switch is activated open.
The CFSound-IV Contact Modules can work with either form of switch by using the appropriate
filename letter token in the filename. A sound can be played when a Normally Open switch
closes
by placing
the ‘C’ letter token after the sound number in the sound filename. In a similar fashion, a sound can be played
when a Normally Closed switch
opens
by placing the ‘O’ letter token after the sound number in the sound
filename.
In the following diagram, Input1 is wired to a Normally Open switch SW1, and Input2 is wired to a
Normally Closed switch SW2. If this contact module is installed on the rear expansion connector, the sound
file to be played when SW1 closes would be named 01C.WAV. The sound file to be played when SW2 opens
would be named 02O.WAV.
1
2
3
4
5
6
7
8
9
10
IN
P
U
T
8
IN
P
U
T
7
IN
P
U
T
6
IN
P
U
T
5
IN
P
U
T
4
IN
P
U
T
3
G
R
O
U
N
D
Normally
Closed
02O.WAV
Normally
Open
01C.WAV
SW1
SW2
G
R
O
U
N
D
IN
P
U
T
2
IN
P
U
T
1
