LCOS offers a basic ABS signal system. To fully use the Signal system, you will need the block occupancy hardware installed for any block you want a signal to monitor.
Signal aspects are determined automatically by block occupancy and turnout state rules that you define using the Servo Manager tool. For CTC operation, automatic operation can be overridden where and when desired while still maintaining automatic operation of other Signals. Signal feedback allows a MASTER control panel to show current signal aspects.
Signal Manager
Navigate to a CLIENT and click 
to start the Signals Manager. Two windows will open: the Signal Manager and the Signals List.
The Signal Manager window comes up with all controls disabled. Adding or loading a signal object will enable controls as explained below.
Creating A Signal
To create a new signal, select the aspects it will show from the “New Signal Aspects” drop-down list, then click Add new Signal.
Six Signal types, defined by the aspects they can show, are available:
- STOP / OFF
- STOP / CLEAR
- APPROACH / OFF
- STOP / APPROACH / OFF
- APPROACH / CLEAR
- STOP / APPROACH / CLEAR
The LCOS convention iis that a signal will show CLEAR or OFF if no condition to set either STOP or APPROACH exists. Those conditions can be block occupancy and/or turnout state.
The new signal will be loaded into the edit window. At this point, the controls related to the turnouts and blocks you have defined on the node will be enabled. In this example, we are creating a two aspect signal — STOP / CLEAR — on a node that has 4 blocks and 3 turnouts. Accordingly, the controls for blocks 0 – 3 and turnouts 0 – 2 are enabled for this signal.
Aspect to Port Map
At the top of the Signal Editor is a section for selecting ports. The first step when creating a new signal is to select the ports to which you have connected the signal.
A signal can use up to 3 digital output ports. By default, the system uses Port A for Stop aspects, Port B for Approach and Port C for Clear. Using the default template, the editor will map single ports to signal aspects. Select the ports in use for this signal on the left side.
The checkboxes in the Aspect->Port Map section on the right determine which ports are turned on for a given aspect. By default, the system assumes one port per aspect and sets default port associations as shown.
Some signals may use multiple ports to represent an aspect. Subject to the 3 port limit, LCOS allows you to define how ports are combined and mapped to produce a signal aspect.
In this example, a conventional 2 LED signal is configured to use one port per aspect. Since this is a STOP / CLEAR signal, the APPROACH line is disabled.
Object Checkboxes and Buttons
To link this signal to a block or a turnout, first select a layout object checkbox. The blue buttons labeled “READY”will change to represent either an aspect (STOP or APPROACH) or, in the case of the button after “CLEAR if aligned”, a turnout alignment selector. When activated, click the buttons repeatedly to cycle between available options; in some cases there may only be one option which cannot be changed.
Continuing with the STOP / CLEAR example, this node monitors 4 local blocks.
This signal protects block 0 only, so only the checkbox for block 0 is selected. Next to it, the aspect selector is set to STOP. This causes the signal to monitor block 0 and, anytime the block is occupied, the signal must set its aspect to STOP.
The example node also has 3 local turnouts. Two of those turnouts are downstream from and protected by the signal.
Checkboxes for the two affected turnouts have been selected.
Turnout 0 is set so the points are facing away from the signal. From the perspective of the signal, the turnout can only be transited if it is set to MAIN. In the middle column the safe alignment is selected and, in the right hand column, the aspect to show when the turnout cannot be transited is specified.
Turnout 1 is pointed the opposite way relative to the signal: its points face the signal. In this case, from the perspective of the signal, the turnout can be transited so long as it is not in motion. Accordingly, for this turnout, the “Motion only” checkbox is selected, the safe alignment is automatically set to ANY and the aspect to show when the turnout is moving is set to STOP.
With these settings, the LCOS Signal Object executes a rule that, if written out, would look like this:
IF BLOCK 0 IS OCCUPIED OR
TURNOUT O IS NOT ALIGNED MAIN OR
TURNOUT 1 IS MOVING
THEN SET ASPECT TO STOP
ELSE SET ASPECT TO CLEARAnother Example
Lets take the basic methods above and apply them to multiple signals on two nodes. Here is a portion of a track plan for a larger layout.
Nodes 4 and 5 are physically adjacent and share track between them. We’ll be programming signals for the Main line; diverging tracks are for sidings, team tracks or a small yard.
Before configuring signals, nodes 04 and 05 have to be configured to listen for each other’s objects (See Basic Layout Objects, Part 1 and Basic Layout Objects, Part 2) of interest, as shown below:
Node 04 Blocks & Turnouts
Node 5 Blocks & Turnouts
Signal S0 on Node 04
This signal faces east and controls west-bound traffic on the mainline from Node 04, Turnout 0 to Node 05, Turnout 4. Here is one way to configure the signal:
In this case, the state of the signal depends on local block 0 and local turnout 0, plus two blocks and two turnouts on adjacent node 05 that this node monitors. Further, not all conditions require a STOP aspect; two remote conditions are deemed far enough away to justify APPROACH instead.
When interpreting these settings, keep two automatic rules in mind:
- CLEAR or OFF are defined as “no other defined condition tests true”; and
- STOP conditions always take priority over APPROACH, which always takes priority over CLEAR/OFF.
So, the rule for S0, Node 04, would look like this written out:
IF BLOCK 0 IS OCCUPIED OR
BLOCK 9 is OCCUPIED OR
TURNOUT O IS NOT ALIGNED MAIN OR
TURNOUT 9 IS NOT ALIGNED MAIN
THEN SET ASPECT TO STOP
ELSE IF BLOCK 8 IS OCCUPIED OR
TURNOUT 8 IS MOVING
THEN SET ASPECT TO APPROACH
ELSE SET ASPECT TO CLEARS1 on Node 04
S1 faces west protects Turnout 0 only, so here we’re creating a STOP/OFF signal. You would likely use additional signals in this area to convey additional information beyond the turnout.
The resulting rule:
IF TURNOUT 0 IS MOVING
THEN SET ASPECT TO STOP
ELSE SET ASPECT TO OFFS0 on Node 05
This signal faces west and controls east-bound traffic from Node 05, Turnout 4 to Node 04, turnout 0.
The resulting rule:
IF BLOCK 3 IS OCCUPIED
OR BLOCK 4 IS OCCUPIED
OR TURNOUT 4 IS NOT ALIGNED MAIN
OR TURNOUT 5 IS MOVING
THEN SET ASPECT TO STOP
ELSE IF TURNOUT 8 IS MOVING
THEN SET ASPECT TO APPROACH
ELSE SET ASPECT TO CLEARS1 on Node 05
This signal faces east and controls east-bound traffic through the interchange from Turnout 5 through Turnout 4 to Block 2. We want to the signal to warn if Turnout 4 is lined for the divergent route since that leads to team tracks or if Block 2 is occupied. For both conditions we want S1 to show APPROACH.
The resulting rule:
IF BLOCK 3 IS OCCUPIED
OR TURNOUT 5 IS NOT ALIGNED MAIN
THEN SET ASPECT TO STOP
ELSE IF BLOCK 2 IS OCCUPIED
OR TURNOUT 4 IS NOT ALIGNED MAIN
THEN SET ASPECT TO APPROACH
ELSE SET ASPECT TO CLEARIn this situation, you could set the aspect if Block 2 is occupied to STOP. However, because STOP conditions take priority, any occupancy of Block 2 would force STOP at S1 even when Turnout 4 is lined for the divergent route. Instead, the best approach in a situation like this is to limit S1’s primary responsibility to the T5 -> T4 section, and assume an additional downstream signal to fully cover Block 2.
Of course, using multiple signal heads (each head is a logical signal) is another way to handle complex intersections.
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