User's Manual

1.3.2.8 Interface CCA Theory
Refer to Figure 1-14. The Interface CCA provides interface connections between the RMS/Facilities/Low
Power Backplane CCAs and the outside world. Examples include spare analog and digital inputs, spare
digital outputs, temperature sensors, smoke detector, intrusion sensor, and a TACAN antenna controller.
RS232 communications are provided to RCSU and PMDT terminals as well as an optional Ethernet
module. All signals are protected by transient voltage suppression (TVS) devices on the Interface CCA
before exiting.
All connections between the Interface CCA and the RMS/Facilities/Low Power Backplane CCAs are
accomplished via headers J1 and J2. The J2 and J3 connections will not be used in a DME system since
there will not be a TACAN antenna system controller.
Connectors J5 and J6 are DB9-types which provide interface to the RCSU and PMDT terminals mentioned
previously.
Connector J7 is an RJ11 phone jack provided for exterior temperature sensing.
Connector J8 is a header provided for in-factory test purposes.
Connector J9 is an RJ45 jack intended for use as an Ethernet port. The port will be powered by a +3.3V
DC-DC converter (PS1).
Terminal block TB1 facilitates connection of up to ten spare analog inputs, four digital inputs, and four
digital outputs.
Terminal block TB2 allows connection of the RCSU and Dial-Up modem tip and ring signals. These
signals are transient protected by common-mode chokes as well as spark-gaps, Sidactors, and power
resistors. INTERLOCK and EXT_KEY_IN signals are TVS-protected and optically isolated. True isolation
for these signals may be enabled or disabled depending on the strapping of JP1 and JP2. EXT_KEY_OUT
signals are optically isolated and TVS-protected before exiting via TB2.
SMOKE_DETECTOR, INTRUSION_SENSOR, ILS-VOR_RX_232, and ILS-VOR_TX_232 signals are
TVS-protected before further routing. DET_IDENT1 and DET_IDENT2 signals are scaled as well as TVS-
protected before exiting via TB2.
Earth ground lug E1 provides a return path for all transient voltage protection devices on the Interface
CCA.