Bronkhorst PROFIBUS-DP slave interface - Manual (Page 22)

BRONKHORST ®
7 SAFE STATE
If PROFIBUS communication problems occur, so when instrument is not in data exchange mode, the
instrument forces the valve (controllers only) into a safe state mode. This safe state depends on the
type of valve. NC valves will be closed, NO valves will be opened fully. The green and red Led on top of
the instrument indicates this mode by a short flash: 0.1 sec on, 2 sec off. As long as there is no data
exchange between master and slave the instrument will stay in this mode. It will leave this mode
automatically when data exchange starts. Via the RS232 communication interface it is possible to force
the instrument out of the safe state by changing the control mode to a value other than 0. At for
example control mode = 18 (RS232) or control mode = 1 (Analog input) the instrument will not get into
safe state.
Page 22 PROFIBUS DP interface 9.17.025