BC9000
The BC9000 is a sign to manage anticollision system in intersection. It does not have routing layer and does not read destination address, making it usable in any rail circuit, not necessarily a ByteCart network.
Note: Since release 2.0.1, BC9000 output is inverted.
Note 2: Since release 2.0.1, BC9000 should be replaced by BC90XX signs when used as subnet exit sign.
It must be associated with any BC90XX sign (except BC9001), including another BC9000 sign.
This sign is placed on a branch that joins the main ring across an intersection, and is associated with another BC90XX on the main branch.
Each sign has an escape track that will be used when intersection is taken by another cart: on the main ring the escape procedure will be to turn left in the subring, and on the branch it will be to make a U-turn. The whole construction must form a 3x3 square. On the picture below, BC9000 sign is under the clear wood block on the branch, while BC90XX sign is under the dark wood block on the main ring.
What BC9000 does is to synchronize its own lever with the lever of the associated BC90XX, giving 2 possible positions : OFF-OFF or ON-ON ( note: since 2.0.1, it's ON-OFF and OFF-ON ). Moreover the position can switch only if there is no risk to break a train.
Giving this rule, the preferred strategy of BC9000 is to power the 2 levers when a cart passes on it, meaning to switch to ON-ON position ( note: since 2.0.1, default behaviour is to switch off its own lever, giving OFF-ON ) whenever possible, providing that no train will be broken during operation.
On the other side, the preferred strategy of BC90XX is to satisfy routing layer, switching to the correct position (OFF-OFF or ON-ON) ( note: since 2.0.1, it's ON-OFF and OFF-ON ) if necessary, providing that no train will be broken during operation.
On both sides, if preferred strategy can't be satisfied in order to avoid collision, one of the track will be deviated to alternate path. In other words, anticollision layer has priority over routing layer.
BC9000 should be replaced by BC90XX signs to close a subnet.
If address layer is not used, BC9000 signs can manage an intersection. Train feature is supported if a ticket is in the cart with train bit set.
BC9000 sign must be placed under a rail. At least a lever should be present on the left or on the right of the sign to command an intersection that can make the cart go straight or turn in escape track. the collision point must be 3 blocks behind the sign. It must be associated with another BC00XX sign placed so that the collision point is also 3 blocks behind it.
A standard collision point (2 tracks become 1) can be managed entirely with 2 BC9000 working together in a ByteCart-unaware network. Train support is provided by routing layer (train flag is written in destination address), so you can use trains only if you use destination address.
Line #1 : Free
Line #2 : [BC9000]
Line #3 : Free
Line #4 : Free