Westermo FD-20 - Manual (Page 28)

28 6630-2220
To ensure that the slaves output remain even at PROFIBUS DP interruption as well as
power supply interruption or restart of FD-20, select the continue data exchange with
slaves at serial transfer timeout (SW1:8) together with selecting “Controlled release of
communication by the application program” in DP Master settings window (accessible
from Master Configuration window), during the SyCon
® configuration
A fully operational PROFIBUS DP network communicating with all slaves (not necessarily
exchanging data) is indicated by an active BA LED. Stat_Diag (static diagnostics) will be
indicated by an active DIAG LED.
As long as the FD-20 is in a run state, the data from the PROFIBUS DP slaves will be
exchanged with a remote fieldbus adapter via the serial transfer line.
Received serial data frames are indicated by the RD LED, even if there are errors.
Transmitted serial data frames are indicated by the TD LED.Transmission will occur after
receiving a correct frame and if the BA and RUN LED are active and the DIAG LED is
inactive, or if Stat_Diag (static diagnostics) is ignored.
7.1 Halt state
The FD-20 is in a halt state if the serial connection with the remote fieldbus adapter has
not been established.The RUN LED will be inactive.
The FD-20 will wait to receive a correct serial frame from a remote fieldbus adapter.
The FD-20 goes into a run state if a correct frame is received and the received data
length complies with the output data length (defined by configuration) and when the FD-
20 is exchanging data with all the PROFIBUS DP slaves.
Note: When the FD-20 receives a correct serial frame the PROFIBUS DP network will
be initiated (SW 1:8 set to OFF).The time to start the data exchange with all
slaves will be dependent on the number of slaves, the slave’s complexity and
PROFIBUS DP data rate. If the start time is so long that a new serial frame is
received, this new frame must be correctly received before the FD-20 goes to a
run state. Only the last received frame will be replied.
7.2 Run state
The FD-20 is in a run state if the serial connection with another fieldbus adapter has
been established, data is exchanging via the serial line and this data is exchanging with
all connected PROFIBUS DP slaves.The BA and RUN LEDs will be active.
If an error free serial frame is received, a reply will be sent after the turning time. (S1:5)
The FD-20 will go into a halt state if the time exceeds the allowed timeout since the last
correctly received frame (S1:6).
Note: If the allowed timeout between received frames is exceeded, this is indicated by
an inactive RUN LED and if “Stop the data exchange with slaves at serial transfer
timeout” (SW 1:8 set to OFF) is selected, the data exchange with all slaves is
stopped.