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Clarify use of 0x3800 for section empty in DCC Detector WN #187

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Clarify use of 0x3800 for section empty in DCC Detector WN #187

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7bbc0a4
clairify use of 0x3C00 for section empty
bobjacobsen Feb 22, 2026
a79c493
fix detector -> decoder typo
bobjacobsen Apr 1, 2026
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21 changes: 18 additions & 3 deletions drafts/generated/DccDetectorWN.txt
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Expand Up @@ -79,14 +79,29 @@

2. If the high bits are 0x39 this represents a DCC consist address

3. An address of 0x3800 (short address 0) represents “unknown”.
3. An address of 0x3800 (short address 0) represents that the track is empty, i.e. there is no
decoder present.

4. Otherwise it’s a DCC long address

The encoding of DCC addresses into 14 bits follows the S-9.2.1.1 and RCN-218 standards.

The 0x3800 value is used for unknown instead of 0x0000 because 0x0000 is long address zero, which is a
valid (though uncommon) long address.
The 0x3800 value is used for track empty instead of 0x0000 because 0x0000 is long address zero, which is
a valid (though uncommon) long address.

A detector may, but does not have to, use the 0x3800 “track is empty” by for example producing a “'track
is empty' leaves” event when the track becomes occupied, and a “‘track is empty arrives” when the track
becomes unoccupied.  For example:



06.80.99.30.03.50.38.00 - "track is empty” leaves

06.80.99.30.03.50.F8.03 - 3S arrives

06.80.99.30.03.50.38.03 - 3S leaves

06.80.99.30.03.50.F8.00 - "track is empty" arrives

2.5 States

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