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C4 Manual Rev 7.5.2
9.5 Installation and Use of TTL Outputs and Input
The C4 has incorporated in it the ability
to receive one TTL signal and send two
TTL signals. Throughout the manual,
the outputs are referred to as
AUX/POWER CONTROL PORT and
REFRIGERATION COMPRESSOR
PORT. The input is referred to as the
AUX INPUT (previously known as the
DOOR SWITCH). These signals are
available on the "B" circuit board (the
one with the 6 lug screw terminal strip
on the back. The connections are
available on pins 6-10 of J6 at the back
of the board. Look for the 5 pin
connector just below the 6 lug terminal
strip. The 5 pin header is pins 1-5 of J6
and the 5 through hole solder pads just below it are pins 6-10.
The J6 pin-outs are as follows:
PIN 6 +5v
PIN 7 Aux Input (Door switch)
PIN 8 Ground
PIN 9 Aux/Power Control (Normally high - See Section 7.7.8)
PIN 10 Compressor Control (Normally low - See Section 7.7.7)
Pin 6 (+5v) is not used. The door open input (Pin 7) should be connected to ground
(Pin 8) to activate the door open signal in the controller. When Pin 7 is connected
to ground, bit 7 of byte 35 of the Error/Status String (See Section 7.8.3) is set.
When Pin 7 is not connected to ground, that bit is reset. Each time the state of
Pin 7 changes (connected or disconnected from ground), bit 0 of the Error Byte
(See Section 7.8.2) is set.
Pins 9 and 10 supply +5v when the port is “on”. The state of both ports is reported
by the Status Byte (See Section 7.8.1) and by the 35 of the Error/Status String
(See Section 7.8.3). In the Status Byte and the Error/Status String, the reporting
bits are set if the port is “on” (+5v) and reset if the port is off.
These ports are TTL level and will require proper isolation and drive capability
considerations when interfacing to other devices. Damage to the C4 from
improper connection or use of these board level facilities is not covered
under your Sigma Systems warranty.