The radio network for the Winter Train v. 2 is based on the wireless JeeNode platform. The JeeNode radio network is a simple package based communication system capable of both broad cast and point to point communication.
Due to limitations in the protocol used by the JeeNodes, the package header can only contain one radio “node” ID - either sender or receiver. In order to simplify implementation and debugging, all communication will be done as “broadcast” (which it anyway is). The package header will contain the sender ID. The first byte of the payload will specify the package type, which normally also will indicate the intended destination.
Based on this, any receiver can identify the sender and the content and hence determine, if the receiver should react on the received package.
Compared to version 1, the specification of a few packets has been changed - details, that were not implemented in version 1.
Node group: 101
|10||RBC_COM||Communication link to RBC|
|20||OBU_1||Train 1 - Stainz 2020|
|21||DMI_1||DMI for train 1|
|23||DMI_2||DMI for train 2|
This ID is used to identify the sender of each package. The OBU node ID is further used as a unique identification of each train towards the RBC.
|10||Status and position Report||RBC_COM|
|20||Poll acknowledgement and operator commands from DMI to OBU||OBU 1)|
|21||Poll of and indication to from OBU to DMI||DMI 1)|
|31||Mode and movement Authority for OBU||OBU 2)|
1) OBU's and DMI's are assigned in pairs - one OBU has only one DMI and vice versa. Hence the receiver ID can be deduced from the sender ID.
2) The intended train will be specified in the packet.
RF12 Package Specification
See enummeration for coding of values.
10, Position Report
Position report from OBU to RBC:
|6,7||int||Actual distance from balise to train, with sign||Distance measured from position of tag reader antenna.|
|9||byte||Status||B0-2: Requested operational mode, B3-4 Nominal driving direction, B5-6: Track polarity, B7: AuthAck|
AuthAck: Acknowledgement for received Movement or Mode Authority FIXME One bit only??
20, DMI acknowledgement
Acknowledgement and commands from DMI to OBU:
|1||Byte||Selectors||B0-2: Mode Selector, B3-4: Direction Selector, B5-7: Traction Selector|
21, Poll DMI
Poll and indications from OBU to DMI:
|1||Byte||MA and error Indication||B0: Green, B1: Yellow, B2: Red, B3: Blue|
31, Movement Authority
MA from RBC to OBU:
|1||byte||Train ID||Same as radio node ID of the OBU|
|8,9||int||Distance from balise to EOA, with sign|
Distance = 0 is a special MA, requesting the train to stop and clearing the MA.