Page 4 of 6
Description of operation
Operating principle of the occupancy detection module
The Occupancy Detector surveys if a there is a contact between
the left and the right track. This contact is created by rolling mate-
rial (locomotive or car) with conducting axles. Three-wire track
conform rolling material is thus required.
Alternatively temporal contacts can be used to make this contact.
The Occupancy Detector constantly checks if on any of the 8 track
blocks such a contact is established and the corresponding ad-
dress bits in the SX-bus is set and the information is available for
the system central unit. Another system device configured for the
same address (e.g. an accessory decoder) can read and display
the status of the 8 track blocks automatically.
Bringing into service
The address of the occupancy detector BMMOT, response delay
and dropout delay as well as additional parameters (options) are
programmed through the SX bus. In order to do so, a controller,
e.g. a central unit ZS1, a controller unit SPF-PIC or a (bus)-
interface with corresponding computer programme are required.
After plugging occupancy detector BMMOT to the SX bus these
parameters can be set.
During programming of the occupancy detector BMMOT the bus
addresses 0 to 3 will be used temporarily. That means during
programming the contents of these addresses will be changed.
Connection scheme
booster range 1: central unit
double sided insulation
track 1 to ...
SX0 SX0 SX1 SX1
PX MX MX RS232
SW2 SW1
2
1
PL2
Selectrix central unit,
e.g. central unit ZS1
booster
3-wire-track
central unit
occupancy
detector
BMMot
detector
BMMot
one-sided insulation
Parameters and Programming
Programming
By programming the address of this module and all further pa-
rameters are set. Here all parameters are explained. Refer to the
last page of these instructions for an example for the programming
procedure.
Convention Bit and Key
In information technology “Bit 0” to “Bit 7” is common.
For model railroaders a numbering of “bit 1” to “bit 8” is much more
convenient, as “Bit 1” becomes equal to “Key 1” or “position 1”.
This convention is used in these instructions.
Overview of parameters
Address 0:Address of this module 1 to 103 / 111 (90)
see table of addresses
Address 1:Response delay 1 to 254 (8)
In steps of 10, 20, 40 or 80 milliseconds
Address 2:Dropout delay 1 to 254 (50)
In steps of 10, 20, 40 or 80 milliseconds
Address 3:Extended options
Occupancy or Free detection
Cycle length of response and dropout delay
Address of this module
The address of this module can be set to any value in the range
from 1 to 111. Note that at certain central units addresses 104 to
111 are reserved for internal purposes during operation and should
thus not be used.
Also, addresses 0 to 3 are often used for programming parameters
of modules. Therefore these addresses should also not be used.
Response and dropout delay
Response delay is defined as the time between the actual detec-
tion of an occupied rail and its reporting to the Selectrix bus.
Similarly the dropout delay is defined as the time between detect-
ing a free rail and reporting to the Selectrix bus.
Both delays can be set to values between 0,01 and 20 seconds in
steps of 10, 20, 40 or 80 milliseconds, (Cycle length for re-
sponse and dropout delay).
Depending on the sensitivity of the model railway layout (rail con-
tacts of rolling material, wiring) different values can avoid flickering
or faulty ghost detection reports.
The response/dropout delay is calculated from the sum of the
values of each position (bit) (1 up to 255), multiplied by the
Cycle length for response and dropout delay (10 milliseconds per
default):
Key 1 2 3 4 5 6 7 8
Value 1 2 4 8 16 32 64 128
Time [s] 0,01 0,02 0,04 0,08 0,16 0,32 0,64 1,28
In the following some examples (Seconds {cycle length}):
Key 1 2 3 4 5 6 7 8
Value 1 2 4 8 16 32 64 128
0,4 {10} - - - / - / - -
0,8 {20} - - - / - / - -
4,0 {40} - - / - - / / -
16 {80} - - - / - - / /
