JMRI: Set Signals at Throat-to-Throat Turnouts Help
Author: Dave Duchamp
Keywords: JMRI help Layout Editor panel

# Set Signals at Throat-to-Throat Turnouts

## Introduction

This tool provides an automated procedure for assigning signals to two turnouts in close proximity oriented throat-to-throat, with the throats connected by a single track segment. This arrangement is used where four tracks come together in a small area, so closely that no signals are placed at the turnout throats. Such a setup is used to model a double-slip turnout, for example, but can also occur in other contexts. Each of the two turnouts may be either right-hand (RH), left hand (LH) or wye (WYE) turnouts. Schematically, the final throat-to-throat setup looks as shown below:

If requested, this tool will place signal icons on the panel at the continuing and diverging legs of the two turnouts, and will set up control logic for specified signal heads. Either one or two signal heads may be placed at each leg of the turnouts. The continuing leg is the track connected when the turnout is "CLOSED", and the diverging leg is the track connected when the turnout is "THROWN".

Prior to selecting this tool, both turnouts must be on the panel connected throat-to-throat by a single track segment, and required signal heads must be in the Signal Head Table. This tool places signal heads only when the main track of the turnouts is vertical or horizontal (or mostly vertical or horizontal) on the panel, so design your panel accordingly. The control logic created by this tool only works correctly if each of the track segments connected to the continuing and diverging legs of the two turnouts is assigned to a different block. It works best if the track segment connecting the two throats and the two turnouts are in a fifth different block, but this is not required.

When this item is selected, a dialog is shown for entry of the names (system or user) of the two turnouts, and the names (system or user) of four to eight signal heads to be assigned to the two turnouts. You may enter both turnout names, or enter only one turnout and allow the program to find the other. To check that the second turnout has been found correctly, click the Get Saved button.

For each signal head, check boxes are available for selecting whether an icon is to be placed on the panel, and whether control logic is to be created for the signal head. Regardless of whether icons are placed or logic is created, Layout Editor will record that the entered signal heads are assigned to the specified turnouts.

When two turnouts are setup using this throat-to-throat set up tool, Layout Editor keeps track of that fact. So if you select Set Signals... in the popup menu of either turnout, you will return to this dialog with both turnouts filled in. If you should later desire to 'unlink' the two turnouts and add signals at their throats, for each of the turnouts, select Set Signals at Turnout..., fill in the turnout name manually, enter signal heads, and click Done.

### The Set Signals at Throat-to-Throat Turnouts Dialog

In the Turnout 1 Name and Turnout 2 Name field, enter the name (system or user) of one or two of the turnouts. If only one is entered, the tool will find the other when the Done or Get Saved buttons are clicked. If the tool cannot find the second turnout, or if the two entered turnouts are not on the panel or not connected throat-to-throat by a single track segment, an error message results. It makes no difference which turnout you call Turnout 1 and which you call Turnout 2.

Signal Head names (either system or user) are entered in the next section. If signal heads at these turnouts have been entered previously, click Get Saved to retrieve the signal head names previously entered. The tool provides for entry of two signals at each of the continuing and diverging tracks of each turnout (as shown in the figure above). These signal heads show the status for moving to the continuing or diverging tracks of the other turnout. First the signal heads located at Turnout 1 - continuing track are entered. The continuing track signal head is required, but the diverging track entry is optional. If only the continuing track signal head is entered, the tool assumes that head is signaling both tracks of the other turnout, similar to when only one signal head is placed at the throat of a single turnout.

Next the signal heads located at Turnout 1 - diverging track are entered. Remember this is the turnout 1 leg that is connected when the turnout is set THROWN. When two heads are entered, the head closest to the points signals the status of the continuing track (the turnout CLOSED track) of the other turnout. Similarly, the signal heads located at Turnout 2 - continuing track and Turnout 2 - diverging track are entered.

If there was a signal head previously assigned to any position, and you enter a different signal head in the same place, the new signal head will replace the previous signal head, and the icon of the previous signal head (if there was one) will be deleted from the panel. Similarly, if you replace a previously assigned Diverging signal head with a blank entry (no signal head), the previous entry is deleted, and there will not be any signal head at that position. If a signal head is changed, you must redo any logic that involves it. In particular, if you delete a diverging signal head, you must redo the logic for the continuing signal head located on the same track.

Check Add Signal Icon to Panel to request that an icon for a signal head be placed on the panel at the turnout position indicated. This tool can only place a signal icon on turnouts that are almost vertical or almost horizontal. If this is not so, a message is printed, and you should place the signal icon manually using the Layout Editor tool bar. Regardless, the signal head name is assigned to the specified turnout position. This assignment is important for setting up logic for other signals down the track.

Check Set up Logic to request that the tool set up signal control logic for a signal head. For each of these signal heads, the tool creates a Simple Signal Logic for that head, and in addition creates a Logix that ensures that the turnout the signal is placed on is not thrown against the leg the signal is placed on. The tool will attempt to setup the logic and automatically fill in entries from the information available. If the tool does not have enough information available to set up the logic, a message results, and you will have to return later after more blocks (with occupancy sensors) and/or signals have been assigned to turnouts and block boundaries on the panel.

### Notes

The tool will set up the Simple Signal Logic to set all signals red if the block containing the two turnouts and their connector track is occupied. If this is not what you want, you should edit the Simple Signal Logic by removing the occupancy sensor of that block.

When setting up logic, this tool will follow track within a block until it finds a signal at the end of the block away from the turnout being signaled. If your layout contains sections that are signaled and sections that are not, to get this tool to set up logic correctly, you may have to create and assign a virtual signal (a signal that does not correspond to an actual signal on the layout) at the unsignaled end of the block that connects track that is signaled with track that is not signaled. (You do not need to add an icon for the virtual signal to your panel, but it must exist in your signal head table, and must be assigned to a turnout or block boundary using a Set Signals ... tool.) If a block ends with an end bumper, no virtual signal is required at the end bumper end.

If a block has an internal turnout (the turnout, and the track segments at its throat and continuing legs are within the block), the program will expect signals at that turnout even if it's not at the end of the block. However, at times the user may not want to signal a seldom used turnout within a block. When following track through a block, the program will skip over unsignaled internal turnouts if Skip Unsignaled Internal Turnouts is checked in the Layout Editor Tools menu. It will always, however, warn that it is doing so. Use this option with caution. There is no signal protecting against a skipped turnout being set incorrectly, so if an unsignaled internal turnout is not set correctly, derailed trains could result.

When setting up the Logix used in the control logic, the tool creates an internal sensor to communicate with the Simple Signal Logic. The Logix will appear in your Logix table, and the internal sensor will appear in your sensor table. The system names of the Logix and internal sensor will be, IX or IS followed by TTT_X_HHH, where TTT is the system name of the turnout where the signal head is located, X is either C or T depending on whether the signal head is located on the continuing (CLOSED) track or the diverging (THROWN) track, and HHH is the system name of the signal head. The purpose of this Logix is to ensure that the aspect of the signal head will be red if the turnout where the signal head is located is switched against the track the signal is on.

This tool sets up three-aspect signaling. When a signal head is showing the status when moving to a diverging route, the tool will set up for limited speed (the least restrictive aspect is not green, but yellow), and the signal will show yellow when it otherwise would show green. You can change this with a simple edit (see below).

If you have a special situation at a signal, you may have to edit the information entered by this tool into the Simple Signal Logic. If you would like four-aspect signaling, you can easily manually edit the logic to achieve this. Similarly, by simple hand edits of the logic, you can add approach lighting. If you don't want yellow when moving to the diverging route, but prefer green, open the Simple Signal Logic for the head you want to change and uncheck Limited Speed. The Simple Signal Logic dialog can be accessed from the popup menu of each signal icon. If your special situation cannot be handled by Simple Signal Logic, you should refer to Logix to tailor the signal logic to your needs.

Please remember to save your panel after using this tool.