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BBT

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Block Brake Timer:

Calculation of block brake time automatically to decelerate linear from enter to in.

BBT Tab


BBT

Enable BBT with the specified steps. (4…16)

Start interval

Default 10; Range 10…100.
This value is used as start for a new BBT record and will be used as the initial timer between the steps.

Max. Difference

Longer diffs will be reduced to this max. to avoid unusable values in case a train did stop or derailed between enter and in.
The default value is 250; 2,5 Seconds.

Correction

At every stop block it is re-calculated; This percentage of the difference is used as correction.
25% is the default value which has been proven to be a good choice.
Use a higher value to speed up the learning curve. 100% can also be used.

From Block

For each route a separate BBT record is used.


Calculation List

To block

The block for which the calculation has been made.

Interval

The interval is in units of 10ms.
This is the time between enter and in and will be divided by the number of steps.

Steps

The actual used steps.

Count

The number of calculations for this BBT record.

Fixed

No corrections will be written in this BBT record if set to fixed.

Updates

No BBT updates are received if Monitoring is off. In this case closing the dialog with OK could erase existing BBT lines.

Modify

Modify the selected interval.

Delete

Delete a selected BBT line.

Delete all

Delete all BBT lines.


Functional description

  • It needs multiple stops in a block for (re-)calculating a right interval; The first times it won't fit.
  • At every stop block it is re-calculated.
    • Longer diffs will be reduced to the max. difference to avoid unusable values in case a train did stop or derailed between enter and in.
  • The brake step is: ( V_enter - V_min ) / steps.
  • The calculation is for each block and will be saved in the Plan/Loco XML file.
  • The enter and pre2in events do not adjust speed.
  • If the BBT is too short the loco will run at V_min until in.
  • If the BBT is too long the loco will run with a higher speed than V_min until in; The loco could run over.
  • After editing the loco Train the previous calculated BBT will probably no longer fit because of the changed load; Extra learning stops are needed.
  • BBT is only for blocks without external stop.
    • Staging blocks with In event at train length is regarded as a block with external stop.


Advices

  1. Do not set the decelerate decoder CV 4 to zero.
  2. The use of event timers will not lead to a stable interval; Reset them to zero!
  3. Use as less brake steps as possible to reduce communication overhead; 10 steps is default and a good choice.
  4. Use at least 28 decoder steps; Better are 128.


Graphic


A Enter speed.
B BBT steps; In this example 10.
C Enter event; First BBT step.
10 Last BBT step.
D In event; Step down to zero speed.
E Zero speed; Loco is in wait or idle mode.
loc-bbt-nl.txt · Last modified: 2018/11/12 08:56 (external edit)