ST950S Plus+ Installation and Commissioning Manual
Table 24. PSU Monitoring Connections (continued)
Pin
Legend
Function
4
GND
Return (not used)
3.15.6. CIC/CTB Interfaces: Lamp Supply
PL20 provides an optional connection to an Outstation Monitoring Unit (OMU), where the OMU can
monitor whether the signals (Lamps) are on or off. The 24V output from the CIC/CTB will normally drive
an external relay (e.g. mounted on DIN-rail on a rear panel) with the relay switching a voltage which is
capable of driving the OMC lamp supply input.
The connection detail is as follows:
Table 25. CIC/CTB Lamp Supply Pin Out
Pin
Legend
Function
1
+24V OUT
+24V to the OMU Input Positive / positive of relay coil (if re
quired)
2
LAMPS ON
Open Drain Output for connection to the OMU input / nega
tive of relay coil
3.15.7. CIC/CTB Interfaces: Passive Safety Auxiliary Supply Control (Not
Currently Used)
This interface provides for the control of an optional Passive Safety Relay. This relay may be used to
isolate the power to auxiliary equipment during a passive safety event.
The connection detail is as follows:
Table 26. CIC/CTB Passive Aux Supply Pin Out
Pin
Legend
Function
1
+24V OUT
+24V to the Positive of the Relay Coil
2
Aux PS D
Open Drain Output for connection to Negative of the Relay
Coil
3
NC
No Connection
3.15.8. CIC/CTB Interfaces: Digital Input
Table 27. CIC/CTB Digital Input Functions
Pin
Legend
Function
1
GP I/P
For connection to one switch contact.
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