Technical data

➣
Every active station "knows" the addresses of the other active stations.
An active station checks the address area between itself and the next
active station cyclically, this is known as the GAP address area. With
this check, the station recognizes whether an active or passive station
has been included in the ring or whether a passive station has been
removed.
The GAP update factor specifies the interval at which an active station
checks its complete GAP address area. When a new station is added to
the ring, it receives the token immediately.
➣
When a station has the token, it can transmit providing its token holding
time has not elapsed. The token holding time is calculated according to
a special method each time the token is circulated and indicates how
long the station is permitted to keep or hold the token. If the token
holding time has already elapsed when the token is received, the
station can nevertheless transmit one high-priority frame.
➣
If an active station has the token and if links to passive stations have
been configured, these passive stations are then polled (e.g. read
values) or data is transmitted to them (e.g. transfer of a setpoint).
DTE
DTEDTEDTEDTE
DTEDTEDTEDTE
DTE
Token rotation (logical ring)
Active stations on bus
Passive stations on bus
Master-slave
Fig. 2.2 Principle of the SINEC L2 Hybrid Access Technique
B8976060/02 System Overview
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