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Extended options
Option occupancy detection at ZE Stop
Most occupancy detectors monitor the block status also when the
central unit is set in Stop mode to disable digital track voltage. In
Stop mode this occupancy detector will indicate monitored track
blocks being free by default.
When automatic control functions are used or when connecting a
trackside signal to the occupancy detector of the following track
block, some undesirable side effects may occur. An example is a
signal showing ‘proceed’ aspect while the track block ahead is still
occupied.
The option occupancy detection at ZE Stop can be configured with
four values corresponding four different decoder behaviours in
Stop mode:
Key 1 Key 2 Behaviour in Stop mode:
Off Off Default behaviour
Off On No change
On Off Block free
On On Block occupied
Default behaviour: In Stop mode normally a block is detected as
free if the decoder is connected to the first or the only SX bus of
the central unit as no track voltage is turned on even if it’s actually
occupied. This is not the case when the decoder is connected to a
SX bus of a second central unit which is set to stop mode since the
SX bus of the first central unit feeding the track is on and not
stopped.
In No change mode the track status is not updated at ZE stop, the
last known status (occupied or free) remains active at the SX bus.
If the central unit is on, each occupancy or free detection is stored
in occupancy detector BMMiba (occupancy detector’s LED blinks
in this case). That allows the SX bus, when powered down, to
recover the last state of the tracks (see storage of occupancy
detection).
In Block Free mode all blocks monitored by the occupancy detec-
tor are reported being free when the central unit is in stop mode.
In Block occupied mode all blocks monitored by the occupancy
detector are reported being occupied when the central unit is in
stop mode.
Option occupancy detection at track power off
Most occupancy detectors will try to monitor the block status also
when there is no power or digital signal on the track due to a dis-
connected wire or short circuit. In such a case the track blocks will
be indicated being free by default. Some decoders will under these
circumstances set the block status occupied.
When automatic control functions are used or when connecting a
trackside signal to the occupancy detector of the following track
block, some undesirable side effects may occur. An example is a
signal showing ‘proceed’ aspect while the track block ahead is still
occupied. Another possibility is a free block indicated being occu-
pied before an entering train has reached the block.
Occupancy detection with power off option can be configured with
four values corresponding four different decoder behaviours in
power off situation:
Key 3 Key 4 When track power off:
Off Off Default behaviour
Off On No change
On Off Block free
On On Block occupied
Default behaviour: When track power is off normally a track is
detected to be free if the decoder is connected to the first or the
only SX bus of the central unit. During short circuit on the rails
ghost detections may occur and thus occupancy or free detection
is not reliable.
In No change mode there is no detection when the track power is
off and the last detection reported to the SX bus remains un-
changed.
In Block Free mode all blocks monitored by the occupancy detec-
tor are reported being free when there is no track power.
In Block occupied mode all blocks monitored by the occupancy
detector are reported being occupied when there is no track
power.
Option occupancy or free detection
Most occupancy detectors signal an occupied track block status by
the bit value On and a block free status by Off.
The occupancy detector BMMiba allows to invert occupancy detec-
tion into a free detection.
The option occupancy or free detection defines the convention of
how occupancy or free information is coded:
Key 5 Occupancy or free detection
Off Occupied = On, Free = Off
On Occupied = Off, Free = On
For instance when using accessory decoders set to the same
address as the occupancy detector with free detection track sig-
nals will have to be connected in the way signalling halt when the
corresponding accessory decoder output is off.
Option cycle length for response and dropout delay
Normally the cycle length for response and dropout delay is set to
10 milliseconds. The maximum delay to be set with this cycle
length is thus 2,54 seconds.
For some automatic control functions it might be useful to increase
the dropout delay (the time a track is still signalised to be occupied
although the train already left the track).
Key 6 Key 7 Cycle length
Off Off 10 ms
Off On 20 ms
On Off 40 ms
On On 80 ms
Doing so allows increasing response and dropout delay up to 20
seconds.
The cycle length is used in common for response and dropout
delay.
Option Storage of occupancy status
If option Occupancy detection at ZE Stop is configured to No
Change by Key 1 Off and Key 2 On, then every time a block status
changes, the new status information is stored in the decoder.
When restarting the system after a shut down the block status
information is retrieved from decoder’s memory to the SX bus
rather from the block detection as the track might still be powered
down by the central unit.
Key 8 Storage of occupancy status
Off Always
On Only if central unit is in Stop mode
The memory of the occupancy decoder BMMiba can store the
block status for about 1 million times which corresponds to thou-
sands of system operation hours. Normally it is sufficient that the
block status is stored just before turning the system off. If the
decoder is set to store the status only when the central unit is in
Stop mode, the block status is not stored in the memory perma-
nently but only when the central unit is set to Stop mode before
turning it off.
Factory default settings
Address of this module: 90
Response delay: 8 (= 0,08 sec.)
Dropout delay: 50 (= 0,5 sec.)
Occupancy detection at ZE Stop: Off, Off
Occupancy detection at track power off: Off, Off
Occupancy or free detection: Off (= Occupied)
Cycle length: Off, Off (= 10 ms)
Storage of occupancy status: Off (= always)
If the address of this module is set to a value greater than 111, it
will be reset to the factory default setting (90).
Setting the address of this module to the value of 255 will reset all
parameters to their factory default settings.
Revert back to previous settings
Entering 0 as address, response or dropout delay reverts the
corresponding value to its previously programmed one.
