Bosch Rexroth ID 40 Manual page 15

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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