Connecting Subordinate Circuits; Connection Of Digital Feedback Modules; Application Example: Block Section Control - tams elektronik GBM-1 Manual

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5. Connecting subordinate circuits

Consumers with a current consumption of up to 500 mA can be connected directly to the
outputs A1 to A4 of the GBM-1 and switched on and off depending on the occupancy status.
The GBM-1 evaluates the income signals against earth. Thus you can connect the outputs of
the GBM-1 to:

the inputs of downstream electronic circuits that switch to ground and consume a current of
max. 500 mA;

relays to switch the inputs of subordinate electronic circuits with a current consumption of
more than 500 mA or to switch circuits requiring to be galvanically isolated;

relays to switch the current at the outputs of subordinate modules.

5.1. Connection of digital feedback modules

In principle, it is possible to connect the inputs of digital feedback modules (e.g. s88 modules)
to the outputs of the GBM-1.
Due to the high sensitivity of the GBM-1, interference voltages from the digital system can
generate false occupancy messages. Therefore, instead of a GBM-1, the GBM-8 and
GBM-8.2** track occupancy detectors optimised for digital operation are more suitable for use
in combination with digital feedback devices.

5.2. Application example: Block section control

Functional principle
In the block section, the section behind the occupied section (seen in the direction of travel)
must be blocked for the entry of a following vehicle and the section behind it must be released
again.
With track occupancy detectors and one bistable relay (RL) per section, a block section control
can be realised. The relays are connected between the inputs E1...E4 of the GBM and the
corresponding track sections and function as switches for switching the track voltage in the
relevant sections on and off.
The control connections of the relay are controlled via the two outputs of the GBM, which are
assigned to the two sections ahead. If the section ahead is occupied, the relay's normally
open contact is opened and the section is thus de-energised (see track sections 2.1 and 2.3 in
the illustration). If the section ahead is vacant again, the contact of the relay is closed again
and the section is thus supplied with current again (see track section 1.4 and 2.2 of the
illustration). If neither of the two sections ahead is occupied, the contact of the relay remains
closed and the section is supplied with power.
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GBM-1