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2.2.1.1 Disconnected
DISCONNECTED
is the base state once the SLK is activated and the self-test has
been completed. The SLK's HF field is not active. No data can be transmitted
between the SLK and an MDT. The SLK status display shows
off
. The SLK is ready to
communicate with the control system via the fieldbus.
2.2.1.2 Connecting
The SLK only switches from the operating state
DISCONNECTED
to
CONNECTING
when commanded by the control system. The SLK's HF field is activated. The SLK
is ready to receive. The SLK status display shows
wai
. The next MDT that enters the
field automatically signs on to the SLK and is ready to communicate.
2.2.1.3 Preconnected
This state comes after the
CONNECTING
state and automatically runs once an MDT
enters the SLK's field, i.e., has signed on to the SLK. The SLK executes data transfers
parameterized beforehand through the fieldbus (prefetch and pretransmit). The
status display shows
pre
. Once all pre-defined transfers are complete, the link state
PRECONNECTED
ends automatically.
PRECONNECTED
can end very quickly, so the
pre
signal on the display is not always visible. If the MDT in the
PRECONNECTED
state leaves the HF field early, the SLK switches to the
ERROR
state.
2.2.1.4 Connected
In the basic configuration, the SLK switches from
PRECONNECTED
to
CONNECTED
.
The status display shows
con
. The control system can now directly access the MDT
data. To do this, read/write commands are sent to the SLK through the fieldbus that
are executed immediately. Data read from the MDT is directly transmitted to the
control system.
The control system ends the
CONNECTED
state with a command to switch either to
DISCONNECTED
or
CONNECTING
. Only then can the MDT leave the HF field. If the
MDT left the HF field early, the SLK switches to the
ERROR
state.
The SLK can also be configured so the
CONNECTED
state does not activate and
automatically switches back to
CONNECTING
or
DISCONNECTED
after completing
PRECONNECTED
. This can be done by configuring “auto mode” (see Chapter 5.3.3
“Auto mode”).
2.2.1.5 Error
The read/write head switches to the “Error” state when it is unable to communicate
with the MDT after several attempts, e.g., because the MDT has already left the HF
field during a
DISCONNECT
request. The status display shows a flashing
E00
. This
can occur, e.g., when the MDT moves past the SLK too quickly, or when too much
data was read or written.
The
ERROR
state can be ended by switched to the DISCONNECTED or
CONNECTING
states.
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