Translation note: Not all terms could be translated. Those terms are marked with a (D) for "Deutsch".
Between the block box and the station it belongs to, there is a connection allowing the block box to control the station, i.e. to lock the exit signals and to set them to stop, and which transfers information from the station to the block about signal and rail contact status. This specification defines the electrical signals and pin-out of the connector.
This standard is basically in line with the interface described in Hp1 2/2001 by René Pabst. There are just some items added or more exactly defined.
A note for the English version: Abbreviations are related to the German version, to keep the labelling of buttons and indicators consistent between the two language versions.
For an assignment of the track contacts three types of routes need to be defined:
15 position D-Sub. Male socket at station, female socket at bock box.
All status contacts connected to pins 1 to 8 shall be insulated electrically against the electric of the station and between each other. The contacts shall be rated for a voltage of 50 V and a current of 200 mA DC with an inductive load. The contacts may be polarised. Optocouplers are explicitly allowed.
While the entrance signal displays a proceed aspect, pins 1 and 2 shall be connected.
While any exit signal of a track leading to the protected line displays a proceed aspect, pins 3 and 4 shall be connected.
Passes a vehicle the track contact of the entrance track or in case of the track types "A" and "C" the single track contact, pins 5 and 6 shall be connected for at least 0.1 seconds. This time should be sufficient to engage a relay.
Passes a vehicle the exit track contact of a type "B" track, pins 7 and 8 shall be connected for at least 0.1 seconds. This time should be sufficient to engage a relay. With track types "A" and "C" pins 7 and 8 remain unconnected, i.e. there is no connection on the station end.
Exit Signal Control
On the input (station) end the operating voltage may have any value up to 30 V and any polarity. The inputs may not be loaded with more than 500 mA.
While pins 9 and 10 are connected an exit signal on a track leading to the protected line may be set to a proceed aspect. The proceed aspect may remain even when the connection between 9 and 10 is opened. As long as the conditions for an exit movement of a train are not met, pins 9 and 10 are not connected by the block box and the exit signals may not be set to a proceed aspect.
As long as pins 9 and 11 are connected an exit signal on a track leading to the protected line may show a proceed aspect. When the connection is opened, all exit signals have to be set to a stop aspect and to be locked in this state. Setting of any exit signal to a proceed aspect is not possible before the contacts are closed again.
The contact between pins 9 and 11 is opened, when the train activates the track contact. Therefore the contact acts as a (D)Signalflügelkupplung. While at the prototype this is part of the interlocking in the station, in this implementation the block box supports the interlocking of the station.
If the station is to be operated without absolute block system, pins 9, 10 and 11 have to be connected by a dummy plug, to allow the operation of the exit signals.
This definition of the exit signal control results in the exit signals being locked with a stop aspect, if the connection between station and block box is opened, .i.e. a safe state is entered like at the prototype. This results in most cases in the need of a relay, using normally closed contacts to set the exit signals to a halt aspect.
Permission Change Lock
Pins 12 and 13 are connected by default at the station end. If this connection is opened the permission may not be passed to the other station. This allows to block the line for (D)Sperrfahrten, which will return to the station. It is planned to insert the needed circuit in the interface. The electrical properties are identical to those for the status contacts at pins 1 to 8.
Pins 14 and 15 of the check loop are permanently connected. There is currently no situation known to me, which would require to open this loop. The connection shall have no contract to other circuits. An open check loop signals an interruption of the connecting line between station and block box.
The status contacts may be loaded up to 30 V and 200 mA. The stated polarity (more positive on the lower numbered pin) has to be insured. The design has to consider that there may be optocouplers in the driving circuit. When relays are used, free wheeling diodes must be added to prevent inductive spikes.
If pins 1 and 2 are connected, the entrance signal displays a proceed aspect.
If pins 3 and 4 are connected, there is an exit signal leading to the protected line displays a proceed aspect.
If pins 5 and 6 are connected, a vehicle is passing the track contact of the entrance track or in case of the track types "A" and "C" the single track contact.
If pins 7 and 8 are connected, a vehicle is passing the exit track contact of a type "B" track. This input is not checked in case of the single track types "A" and "C".
Exit Signal Control
The outputs for the exit signal control shall be insulated electrically against the block circuit. There is no polarity defined. Relay contacts are the easiest but not the only solution. The contacts shall be rated for a voltage of 100 V and a current of 500 mA DC.
Remark: The 100 V are necessary for the voltage peaks when switching off inductive loads like relay. It would be possible to reduce this value, if free wheeling diodes would be made mandatory at the inputs of the station circuit.
In case the conditions for a train to leave are met (block clear, permission granted, no exit to that line since the last (D)Rückblocken) the pins 9 and 10 shall be connected.
Is the block occupied or the permission has been passed with track types "A" or "C", the connection between 9 and 11 shall be opened, to lock all exit signals leading to the protected line with a stop aspect.
Permission Change Lock
If pins 12 and 13 are not connected, the permission may not be passed to the other station. In this case the line is blocked for a (D)Sperrfahrt. No signals will be operated and there will be no pre or (D)Rückblock. The electrical properties are identical to those for the status contacts at pins 1 to 8.
If the check loop (connection between pins 14 and 15) is opened, the control line has been interrupted or there is a similar fault. At minimum any permission shall be cleared. But it is allowed to reset all units in the block box to their power on state.