Configuring Abel to use bell sensors

If you are using Abel with externally connected bells, you must tell Abel how they are connected before it will recognise them. To do this, click on the Options menu item and then on External Bells. The following dialog will be displayed:

The purpose of this dialog is to tell Abel which external bells are connected to which serial ports of the computer, and what types of signal they will send to that serial port. You can specify up to 16 external bells using this dialog.

For each bell you want to connect to Abel:

Note. If you have an external bell mapped to bell number 1, this does not mean that external bell is always going to ring as the Treble in Abel. It just makes it the first manual bell, and you can choose which of Abel's bells it rings. So, if you have only one external bell connected to Abel, configure this to map to bell number 1. Then, when you select a method to ring, you can choose to ring the 4th or the tenor if you like, without having to change configurations. Similarly, if you have 6 bells connected, configure them as bells 1-6. And if you're using David Bagley's Multi-Bell Interface, again you must use the lowest numbered bells.

If you are using bells connected to serial port control signals (see above), Abel detects signal transitions, and you need to tell Abel how many transitions to expect for each strike of the bell. So, for example, if you are using optical sensors with two reflectors on the wheel (see Optical Sensor Design), Abel will receive two signals (on and off) as each reflector passes the sensor head – four signals in all. In this instance, with the reflectors positioned as shown in the diagram in Optical Sensor Design, you actually want Abel to ring the bell as it receives the third of these signals (that is, the 'on' signal as the bell approaches the end of its rotation). To do this, set Control Signals so that it says "Ring on 3 of 4". If you were using 'bottom dead centre' sensors, with only a single reflector on the wheel, you'd configure "Ring on 1 of 2".

In addition, for bells connected to serial port control signals, you should tell Abel whether the sensors are 'active high' or 'active low': that is, when a activator passes the sensor, does the signal transition from low to high (the most common case) or from high to low. Tick the 'Sensors Active-High' box for the former; untick it for the latter.

Debounce bells/switches

This control lets you choose a debounce period, in milliseconds. This is useful if you have simple mechanical switches for your external bells or controls, since Abel will ignore signals that arrive within this configured number of milliseconds. The maximum value is 100 milliseconds and the default value 20 milliseconds, though these figures are rather approximate. If you find that your bells ring several times instead of just once when you use external bells, you can try increasing the debounce period.

Clear mappings

This button will clear all the mappings, blanking all the Map to boxes, so that you can choose again how you relate external bells to Abel's bells. It does not clear the details of control signals, or the "Ring on x of y" settings.

Reset 1:1 mappings

This button sets all the mappings for you. External bell 1 will be mapped to Abel's first manual bell, external bell 2 to Abel's second manual bell, etc. This is normally what you require.


David Bagley's Multi-Bell Interface (MBI) is designed to detect when a turning bell passes bottom-dead-centre, and then send a signal to Abel after a fixed time. You have to tell Abel how long this time should be, for each bell, and Abel will send this information to the Interface when you click the OK button on the External Bells dialog. Similarly, if you connect a sensor with a single bottom-dead-centre activator to one of the PC's COM port control signals, Abel can apply an appropriate fixed delay to the signal. In either case, you click on the Sensor Delays button, and a new dialog will appear.

If you are using a single bottom-dead-centre activator for each sensor and not using a Multi-Bell Interface, click the box "Abel Applies Delays (no MBI)". You can also do this if you are using an MBI-like sensor controller that does not expect to receive delays from Abel (you can set the delays to zero, to prevent Abel applying an extra delay in software).

You should set the Delay values as follows:
For each connected bell, ring the bell at normal speed, unsilenced, and adjust the value of the corresponding Delay so that Abel strikes at the same time as the real bell. Each time you adjust the Delay, click Apply before testing the striking again. When all the bells are striking correctly, click OK and then Options>Save.

When you are using bottom dead centre sensors, and using Abel for silent practice, Abel can provide a somewhat realistic simulation while ringing up and down, by not sounding the backstrokes at the bottom of the raise/lower. To make this work as well as possible, you need to set the values for "Treble double clappering" and "Tenor double clappering" to match your own bells. To do this, turn on Abel then, with the bells down and not silenced, start to ring up the treble in just the same way as you would if ringing up in rounds (chiming the bell, and ringing up at a normal rate). After a few pulls, both the real bell and Abel will start double clappering. Adjust the value of "Treble double clappering", clicking Apply after each adjustment, until the real bell and Abel start double clappering on the same pull. Repeat this for the tenor.

After you have set the delays, click on Apply to make the changed values take effect immediately and return you to this dialog, or click on OK to return to the External Bells dialog. Any changed values will also be applied when you click the OK button on the External Bells dialog.

You don't need to use this Delays dialog if you are not using sensors with a single activator.

Timing of External Bells

If you are using the Moving Bells display with an external bell or dumbell, you may find that you have to consistently follow the on-screen bells very closely to get good striking, eg in Rounds. Alternatively, you may find you have to consistently leave a larger than expected gap over the bell you're following. This is because the Moving Bells are set to sound 80% of the way through their bell movement, but the external bell may strike significantly earlier or later than this. If so, you can change the striking characteristic of the Moving Bells, eg to 75% if you're having to follow closely, or 85% if you're having to leave a big gap. For details, see Adding your own Bell Pictures.

Saving options

When you have finished configuring your external bells, click on OK on the External Bells dialog. Now click on the Options menu item and then Save Options to save your settings in the current options file (or Save Options As… if you want to save to a different file).

See also:

  Connecting external bells
  Configuring Abel to use control switches
  Debugging external connections