Version 1.1.11 of SigScribe4 marks the introduction of a significant forward step in MODRATEC's interlocking design software in that conditional locking may now be included.


SigScribe4 - Documentation - Version 1.1.11+


Version 1.1.11+


SigScribe4 version 1.1.11 is a step towards SigScribe10. SigScribe10 is being developed as a bigger-and-better interlocking design tool and simulator. It will offer greater versatility in terms of interlocking options including conditional locking. SigScribe4 version 1.1.11 borrows the locking algorithms of SigScribe10 to enable users to specify conditional locking.

The release of version 1.1.11 corresponds to the ability of MODRATEC to supply Lever Frame Kits that can implement conditional locking.

Conditional locking is important where it is desirable to maintain maximum operational flexibility when signals may be cleared for one of a number of routes. This finds particular application in Speed Signalling. Consequently it is particularly appealing to modellers of railways using american-style signal principles. It is also relevant to modellers of british-style systems where shunt signals often apply to multiple routes.

What is Different in 1.1.11

The following changes have been made:

  • A new item has been added to the Interlocking menu - Interlock from Table.... This allows the user to select a file containing a table of interlocking definitions for the frame being designed. See below for information about the format of an interlocking table file.
  • A new item has been added to the Interlocking menu - Clear all connections. This will remove all lever connections and route definitions for the entire frame being designed. The intended use is when a design has become messy and you want to start again while retaining the existing layout as a skeleton.
  • A new item has been added to the Interlocking menu - Clear all route definitions. This will remove all route definitions for the entire frame being designed. The intended use is when a design has become messy and you want to start again while retaining the existing layout and lever connections as a skeleton.
  • Feedback has now been added during the process of creating the mechanical design of a frame. The process may have been initiated by either the Set Interlocking or Interlock from Table... menu item. If the process takes a significant time, then a progress bar at the bottom-right of the frame will become active. When the process completes, an information panel will indicate the number of iterations used in creating the design.
  • When interlocking is active, a C is appended to the indication of the number of slots if conditional locking is required.

Creating an Interlocking Table

SigScribe4 does not have the ability to visually define multiple signal routes. Consequently, in order to define conditional and other complex interlocking, a text file needs to be created. (Note that SigScribe10 will allow full visual definition of multiple routes.)

An Interlocking Table File (itf) can be created using your computer's default text editor (not a word processor unless it can save as plain text). The file must be saved with the extension .itf . It will be best to save the file in the same folder/directory as the corresponding .ss4 file defining the layout and lever order. If defining interlocking by using an itf file, then there is no need to define any routes within SigScribe4, in fact, any such definitions are ignored when interlocking from a table. Please refer to A TEXT-BASED CODING SCHEME TO DEFINE INTERLOCKING for detailed information. You can download a PDF version for printing here.

When you start SigScribe4 version 1.1.11, it will add two files to your signal diagrams folder/directory. (These files are included with the Linux distribution although not loaded into any specific location.) One file is Conditio.ss4 and contains the signal diagram and frame layout for a conditional interlocking example. There are no route definitions within this file. The second file is Conditio.itf and contains the interlocking table corresponding to Conditio.ss4. You can use these as a way of becoming familiar with how to use text-based interlocking definitions.

You can open Conditio.ss4 in SigScribe4 in the normal manner. Then select Interlock from Table... from the Interlocking menu. Select Conditio.itf. Once the process of interlocking design is complete, click OK on the information panel to enable the simulation. Of particular note is the conditional locking between levers 2 and 7. These two levers can be operated independently except when lever 4 is reversed (this requires lever 3 to be pulled first). When 4 is pulled you will find that either 2 or 7 may be pulled but not both at the same time.

To see the contents of the itf file, you can open it in your chosen text editor. The default text editor for Windows machines is Notepad, and for Mac computers it is TextEdit.

The following basic principles will be helpful when creating an interlocking table. It is not intended as an exhaustive list but will suffice in most model situations.

  • A signal lever should generally require any other signals on the same post to be normal.
  • A signal lever requires points to be set for the required route including, where applicable, points within any overlap.
  • A signal lever requires points to be locked for the required route (British practice typically requires this only for facing moves through points).
  • A signal lever may require other off-route points to be set in a particular way and/or locked in order to provide flank protection.
  • A signal lever requires any other signals that permit access to the signalled route to be normal.
  • A signal lever requires any other signals controlling sub-routes within the signalled route to be reversed. In British practice this applies to a distant signal which requires following stop signals to be off (lever reversed), and to main stop signals whose signalled route contains auxiliary (shunt) signals.

When SigScribe4 processes an itf file, it rationalises the locking in order to eliminate redundancy. In some cases this may mean that even though conditional locks have been specified, they may be eliminated as redundant. Check the slots number to see whether or not a C is shown.

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Show Symbols Panel


The Basics of SigScribe4

Simple Tutorial

Advanced Tutorial

The Principles of Railway Signalling

Using the Symbol Tables


New for Version 1.1.11+

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