Nor-Cal Intellisys Adaptive Pressure Controllers - Manual (Page 20)

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APC-OP-LIT 1/12
\Position Control Select In\
Position Control Select is an ACTIVE LOW TTL input that should be referenced
to Digital Ground. Pulling this pin low will cause the APC controller to use
the analog set-point value as a position command, provided that \Analog Set
Point Control Select\ is also pulled low. Leaving it high will by default cause
the controller to perform pressure control.
Power + 24V DC in
This is the positive terminal of the device power differential voltage input on
DC powered controllers. When referenced to the negative terminal (Power
RTN input), the differential voltage input should always be in the range of
24V ± 10%. The voltage input across these terminals provide the
operating power for the device.
Power RTN
This is the negative terminal of the device power differential voltage input
on DC powered controllers. Use this as a reference to the positive +24V DC
power input.
Reserved
This pin is connected inside the controller, but its function is not
assigned. Do not connect any external device or signal to this pin
as APC damage may result.
RS232 RX
Used for data transmitted from the host to the APC
controller, whenever RS-232 communications are used.
RS232 TX
Connect to this pin for data transmitted from the APC controller to
the host computer, whenever RS-232 communications are used.
RS 485 (A) and RS 485 (B)
Used to transmit and receive RS485 data - half-duplex, multi-drop compatible.
TTL Output Common
This pin should be used as a reference to all TTL outputs
(i.e. Fault, Valve Open and Valve Closed).
\Valve Closed Out\
Valve Closed Output is an ACTIVE LOW TTL output that should be referenced
to TTL Output Common pin. This pin will be low only when the valve is closed.
\Valve Initialization Enable In\
This function is an ACTIVE LOW TTL input that should be referenced to Digital
Ground. Used exclusively for sealing throttling valves (i.e. not for butterfly
valves), it issues the “clear to initialize” command needed to cause the con-
troller to exit out of the safe mode it enters upon power-up. Also required to
remain low for normal TTL valve operation.
\Valve Open Out\
Valve Open Output is an ACTIVE LOW TTL output that should be referenced
to TTL Output Common pin. This pin will be low only when the valve is open.
\Zero Gauge Select In\
This function is an ACTIVE LOW TTL input that should be referenced to Digital
Ground. Pulling this pin low will “zero” the CDG output in software. This
function can only be activated if the actual CDG signal is less than 500mV. If
two gauges are used, then this function acts on both gauges.
7.0 - Analog / TTL Interface
(continued)