Automatic Bell On ESU Decoders - Updated 2022-10-16

As most model railroaders know when a locomotive’s bell starts to ring it is a warning “Look out, I’m moving”! The de facto standard to turn on the bell is function 1 (F1) and when pressed it starts to ring immediately and to turn the ringing off press F1 again or else it would ring continuously (blah!!). What if we changed things a little to have an automatic bell, i.e. press a function key and from then on when the engine is given a drive command the bell will start ringing and also stop ringing when a certain speed (call it S1) is reached. Also, we would like the bell to start ringing again when slowing and its speed drops below S1 and continuing until either it’s accelerated again beyond S1 or stopped in which case it stops ringing. This would be prototypical and similar to the engineer handling the bell without us having to worry about it.

As Ted Wentz showed on the LokSound groups.io forum this is not difficult to do if you have some experience with modifying ESU sound schedules. That would include doing some of the modification tutorials I’ve given in previous posts such as this one. I've taken Ted's demonstration and modified it to prevent the throttle from prematurely turning off the bell while the engine is still moving.

Before we begin, ESU has added the Auto Bell On/Off Template Pack to many of their sound files for modern engines on Function 2 to ring the bell when the horn sounds. You can read about controlling this in any sound file’s accompanying bulletin that has this functionality. The problem this creates is it will interfere with the auto bell feature we’re going to create on engine moving and engine stopping if the engine gives the standard two horn blasts to indicate forward movement. This tutorial assumes that the ESU auto bell feature is turned off.

We’ll use the ESU sound file S0539-LS5H0DCC-Diesel-EMD-12-645E3-T-V4-R4.esux located here. Let’s get started and you’ll see how easy it is.

First, in the Sound pane Overview sheet you’ll see that slot 2 is empty. Create an empty sound slot sound file by double clicking on it and naming it Auto Movement Bell. Add a container and connect it to mute using 2 transitions as shown in fig 1. Call the container Bronze Bell. We’ll come back to this shortly.

Figure 1 After creating the Bronze Bell sound slot

Double click on the container then drag and drop one of the bell loop files from the sound collection in the lower right corner to the created state. We’ll just pick the first one. Add 2 basic transitions as shown in fig 2.

Figure 2 Inside the Bronze Bell container

That’s all there is to the state so we’re done with it. Now, back to the container and its transitions which are the heart of the sound file.

Add 3 grouped conditions:

•     function = true
•    Whatever function you assign to this sound file must be “on”

•     speed > 0
•     don’t start the bell until the engine starts moving

•     speed < SoundCV16
•     use speed to determine when to turn off the bell

This is shown in fig 3.

Figure 3 The grouped conditions

Wait!? What’s this SoundCV16 thing? First off, if we put a hard coded value such as 40 here then if we ever want to change it we would have to go back into the sound file, change the value and then write the entire sound file to the decoder again (another half hour!!). By changing it to a SoundCV we can change the SoundCV value on the Sound Slot Settings sheet of the decoder pane and then just write the decoder values (about 20 seconds). See fig 4.

Figure 4 SoundCV16

There is almost always a free SoundCV available but I say almost because I have seen sound files where there were none.

<Update>There is another variable that can be used in place of SoundCVs. At the bottom of the Sound Slot Settings pane is the Sound Configuration variable shown in fig 5. 

Figure 5 Sound configuration variable

This is different for each sound slot and relates to the "select" variable in the conditions drop down of the sound slot schedule shown in fig 6.

Figure 6 The "Select" variable

This will do the same thing as the above mentioned SoundCV. The difference between the two is the Sound Selection variable is particular to a sound slot (local variable and all sound slots have one) while a SoundCV applies across ALL sound slots (global variable and can be called from any sound slot). Your call on which one to use.

The last step is to assign the new sound slot sound file to a function key on the Function Mapping sheet of the Decoder pane and make certain to also assign the “Drive” condition to the slot shown in fig 7. You could also set the checkbox “Play only if the drive sound is enabled” on the sound slot settings sheet.

Figure 7 The Drive condition assigned to F1

Utilizing the Simulator you can test this to make sure the bell sound you chose is what you want. Notice there are several different bell loop sound files included, some good, some not so good, so pick the one that works for you. Also note that you can use any function number you want to. It doesn’t have to be function 1 as shown in figure 5.

Next up will be automatic horn forward and reverse start and stop signals

Enjoy!

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