OSEK/VDX
Fault-Tolerant Communication
Specification 1.0
OSEK FTCom 1.0 © by OSEK 3
Table of Contents
1 Introduction...........................................................................................................................5
1.1 System Philosophy..........................................................................................................5
1.2 Purpose of this Document ...............................................................................................6
1.3 Structure of this Document..............................................................................................7
2 Summary...............................................................................................................................8
2.1 Architecture of a OSEKtime System...............................................................................8
2.2 Constraints on the FTCom and the underlying Communication Controller.......................11
2.3 Message Exchange Interface.........................................................................................11
3 Message Handling................................................................................................................12
3.1 Messages and Message Instances.................................................................................13
3.2 Message Copy Functions..............................................................................................13
3.2.1 Receiving Messages................................................................................................13
3.2.2 Sending Messages ..................................................................................................14
3.3 Message Frame Mapping .............................................................................................14
3.4 Packing/Unpacking Messages.......................................................................................15
3.5 Byte Order...................................................................................................................16
3.6 Message Send Status....................................................................................................16
3.7 Notification Mechanism................................................................................................17
3.8 Replication/Redundancy................................................................................................17
3.9 Replica Determinate Agreement (RDA).........................................................................18
3.9.1 Message RDA Status..............................................................................................18
3.9.2 Example: RDA “average”........................................................................................19
3.9.3 Example: RDA “majority vote”................................................................................19
3.10 Message Filter..............................................................................................................20
3.10.1Message Filter Function..........................................................................................20
3.10.2Message Filter Status..............................................................................................22
3.11 Overview Message Handling API .................................................................................22
4 Other FTCom Functions ......................................................................................................24
4.1 Time and Synchronisation Services................................................................................24
4.1.1 Assumptions ...........................................................................................................24
4.1.2 Requirements..........................................................................................................24
4.2 External Clock Synchronisation.....................................................................................25
4.2.1 Generation of External Correction Value..................................................................25
4.2.2 Write Correction Value to Communication Controller..............................................26
4.3 Node Membership Service (optional)............................................................................26
4.4 Lifesign Update ............................................................................................................26
4.5 Start-up........................................................................................................................26
5 Inter-task Communication....................................................................................................27
5.1 Communication between OSEK Tasks .........................................................................27
5.2 Communication between OSEK and OSEKtime Tasks.................................................27
5.3 Communication between OSEKtime Tasks...................................................................27
6 Specification of FTCom System Services .............................................................................28
