Specifications

RailCorp Engineering Manual — Signals — Equipment Manual

Cerberus Level Crossing Monitor Field Equipment Manual TMG E1261

Issued August 2012 UNCONTROLLED WHEN PRINTED Version 2.1

When +5V is applied to pin 1 of the D15 connector, the indicator LED (LD1) is illuminated

and current flows across pins 1 & 2 of the AQV214H optoisolator (U1) and illuminates the

internal LED which turns on the internal phototransistor and enables the output. The

output is a voltage free contact (i.e. it can be likened to a relay contact). When enabled

the contact is closed and a 'short' exists across pins 5 & 6 of U1 (actually the resistance

between the pins is about 10 Ohms).

When 0 VDC is applied to pin 1 of the D15 connector, the indicator LED (LD1) is

extinguished and no current flows across pins 1 & 2 of the AQV214H optoisolator, the

internal LED is turned off and the phototransistor is turned off, so that the output of U1 is

disabled (i.e. an open circuit exists between the output pins).

Each output circuit can drive (nominally) up to 120 mA at voltages up to 120 VDC. This

means an output can drive, for example, a non-vital relay, two Q-type relays, up to 5

LEDs, or a sonalert.

This particular Output Optoisolator Board cannot switch AC voltages.

The 5 VDC is fed to the board via the Cable. Test points next to the connector is used to

verify that +5 VDC is present.

All of the '+' terminals of each individual output are bussed together and connected to the

B12 terminals.

The 8-way green connector has each of the 8 switched outputs for connection to the

control devices.

2.6.4 Configuration

There are no configurable items.

2.6.5 Troubleshooting

If there is no power supplied to the Output Optoisolator Board then all outputs are 'off'.

Two categories of failures are examined, multiple failures on board and single output

failures. The 'Multiple failure' section identifies failure points that will most likely effect

more than one circuit. The 'Single Output Failure' section provides a comprehensive fault

finding procedure of one output circuit. In the event of a multiple output failure is rectified

by following the multiple output failure procedure, the technician should then refer to the

single output failure section.

2.6.6 Multiple Output Failures On One Board

If the Outputs are permanently OFF then:

Confirm that the monitor is operating correctly and that the NO FAULT and NO

WARNING LEDs are lit on the monitor front panel.

The fault is most likely to be a power supply or connector problem. Check the LEDs on

the suspect circuit board.

If the LEDs are extinguished check:

Cable connection

Check the +5V to GND test point next to the D15 connector using a multimeter

Replace Output Opto Board