Real-Time Protocols
3
IEC Train Communication Network
IEC 61375 - Clause 2
1999 December, HK
TCN Data Traffic
Periodic Transmission
short and urgent data items
carrying the trains's state
Since variables are refreshed
periodically, there is no need for
a retransmission protocol in
case of transmission error.
Two traffics share the same bus:
periodic
phase
periodic
phase
event
sporadic
phase
sporadic
phase
time
Sporadic Transmission
infrequent, sometimes lengthy
messages reporting events, for:
• System: initialisation, down-loading, ...
Since messages represent state
changes, they may not get lost
a protocol recovers transmission
errors.
• Users: diagnostics, status
basic period
basic period
Process Data Message Data
... motor current, axle speed, operator's
commands,...
