ISO 11898-4:2004 道路車両—コントローラーエリアネットワーク（CAN）—パート4：時間トリガー通信 | ページ 6

3.1

application watchdog

entity which verifies that the application is operating properly

3.2

arbitrating time window

time window assigned to messages that share the same time window

3.3

basic cycle

row of the system matrix of several consecutive time windows

3.4

Cycle_Time

difference between the local time of an FSE and its Ref_Mark

3.5

Cycle_Count

number of the current basic cycle of the matrix cycle

3.6

Cycle_Count_Max

value of Cycle_Count of the last basic cycle in the given system matrix of the network

3.7

Cycle_Offset

parameter specifying, within a matrix cycle, the first basic cycle for which an Rx_Trigger or Tx_Trigger is valid

3.8

Disc_Bit

part of the reference message signalling a discontinuity in global time caused by an external clock correction by the time master

3.9

error severity

levels of distinguished severity of an error

3.10

exclusive time window

time window assigned to a specific message transmitted periodically without competition for the CAN bus

3.11

Expected_Tx_Trigger

local parameter which specifies, for each FSE, the number of Tx_Triggers the FSE is expected to activate between two starts of a matrix cycle

3.12

Frame_Synchronisation

pulse, generated in each FSE and for each data frame and remote frame in the CAN network at the sample point of start of frame (SOF) bit, synchronous in the whole network, disregarding signal propagation times, and with an optionally added time offset referencing to the sync_segment of the SOF-Bit, to compensate for variations of bit timing configuration in the system

3.13

frame synchronisation entity

FSE

part coordinating the operation of logical link control and media access control

Note 1 to entry: Each CAN controller in a time-triggered CAN network has its own FSE.

3.14

free time window

time window free of messages scheduled in the system matrix

3.15

global time

node view of the global time of the current time master

3.16

Global_Ref_Mark

parameter saved on successful reception of a reference message

3.17

Global_Sync_Mark

current value of the node view of global time, saved at the pulse of Frame_Synchronisation

3.18

Init_Watch_Trigger

value of the maximum of cycle time

3.19

Initial_Ref_Offset

initialisation value that loads the Ref_Trigger_Offset

3.20

level

level of implementation of time-triggered CAN in accordance with this part of ISO 11898

Note 1 to entry: There are two levels, Level 1 and Level 2, with Level 2 an extension of Level 1.

3.21

local time

time generated by a cyclic incrementing counter

3.22

Local_Offset

difference between Global_Ref_Mark and Ref_Mark, saved at each successful completion of the reference message

3.23

master state

vector which combines the FSE states referring to error, synchronisation and master-slave relation, i.e. a triplet (error level, sync_mode, master-slave_mode)

3.24

Master_Ref_Mark

MRM

parameter transmitted by the time master in the reference message

3.25

matrix cycle

cycle of all basic cycles in the system matrix, consecutive from the first to the last basic cycle

Note 1 to entry: The matrix cycle is the same as the basic cycle if the system matrix consists of one basic cycle only.

3.26

merged arbitrating time window

single window into which consecutive arbitrating time windows are merged

3.27

message object

buffer providing storage of an LLC frame together with control and status information

3.28

message status count

MSC

error counter providing means for detecting scheduling errors for messages sent in exclusive time windows

3.29

network time unit

NTU

unit measuring all times and providing a constant of the whole network

3.30

network view

system aspect of network parameter

3.31

node view

local aspect of network parameter

3.32

node view of global time

integer part of the sum of local time of the node and its Local_Offset

3.33

potential time master

frame synchronisation entity that is allowed to send a reference message by system configuration

3.34

Ref_Mark

parameter saved on each successful completion of the reference message

3.35

Ref_Trigger_Offset

parameter used to modify the time mark within a Tx_Ref_Trigger such that it sends a reference message

3.36

reference message

message (data frame) that starts a basic cycle

3.37

Repeat_Factor

parameter specifying the repetition rate of a message within a transmission column, being a part of Tx_Trigger or Rx_Trigger parameters

Note 1 to entry: The unit of the repetition rate is “rows in the system matrix”.

3.38

Rx_Trigger

parameter that specifies when the successful reception of a message will be verified

3.39

Sync_Mark

current value of the local time saved at the pulse of Frame_Synchronisation

3.40

system matrix

form containing all messages of all nodes in the network, organised as components and consisting of time windows organised in basic cycles (rows of the matrix) and transmission columns (columns of the matrix)

Note 1 to entry: The system matrix specifies the correlation between messages and time windows (type and time mark). The first basic cycle in the system matrix starts with Cycle_Count 0.

3.41

time gap

time between the end of a basic cycle and the beginning of the next basic cycle, when the beginning of the next basic cycle is synchronised to an event

3.42

time mark

mark within a frame synchronisation entity specifying an instant of Cycle_Time (in NTUs) at which a certain action is expected or planned

3.43

time master

frame synchronisation entity sending the reference message

3.44

time window

amount of time allocated for a specific transmission column in the system matrix

3.45

transmission column

column of the system matrix whose elements correlate to a particular time window repeated in each basic cycle

Note 1 to entry: Transmission rows are the basic cycles of the system matrix.

3.46

time unit ratio

TUR

ratio between the length of a NTU and the length of the FSE specific basic time unit (e.g. local oscillator period) used for clock synchronisation

Note 1 to entry: TUR is, in principle, a non-integer number. The node view of a NTU is implemented by the value of TUR.

3.47

Tx_Count

counter that is reset at each start of a matrix cycle, i.e. after identification of the corresponding reference message with Cycle_Count equal to zero

3.48

Tx_Enable

time period within which the transmission of a message may be started

3.49

Tx_Overflow

status flag set when more Tx_Triggers occur than specified by Expected_Tx_Trigger

3.50

Tx_Ref_Trigger

special Tx_Trigger parameter referring only to the triggering of reference messages

3.51

Tx_Trigger

parameter specifying when a certain message will be transmitted and which consists of a time mark, the position within the transmission column in respect of the first sending (Cycle_Offset) and the repetition rate (Repeat_Factor) within that transmission column, and a reference to a message object for which the Tx_Trigger is valid

Note 1 to entry: The Tx_Trigger also contains information about the window type (exclusive, arbitrating, merged).

3.52

Tx_Underflow

status flag set when less Tx_Triggers occur than specified by Expected_Tx_Trigger

3.53

Watch_Trigger

time mark used to check whether the time since the last valid reference message has been too long