FCM 300 / FCD 300 / VLT
®
2800 / DP V1 PROFIBUS
Profibus
DP
■ Clear Mode / Fail Safe
If the PLC /Ma ster functions are seriously disturbed, the
DP master will go into Clear Mode. The D rive can be
programmed to react in va rious ways on that incident.
Theseoptionsareshowninthetablebelow.
The drives which support the DP V1 features,
basically support the Fail Safe function for Clear
Mode as stated in the GSD attribute Fail_safe = 1.
Fail Safe me ans, that the slaves safely detect a clear
state of the master. The reaction however must be
programmed as shown in the table below.
For masters, that do not support Fails Safe Clear,
the drive will have the same reaction on a clear
mode as for Fail Safe Clear.
If a Clear appears, the control word and speed
reference is set to zero in the drive. The reaction
of the drive, however depends on the setting
of parameter 805 (control word validity) and
parameter 804 (Time Out function).
P804 P805 Drive Behaviour on Clear mode
Off Bit 10 = 1, Control Word valid The drive will continue with the previous sen d valid
Control word and speed reference
Off Bit 10 = 0, Control Word valid The Drinve Control Word and Speed Reference w ill
be set to zero, w hich will cause the drive to stop.
Off No function: Control Word always valid The Drinve Control Word and Speed Reference will
be set to zero, w hich will cause the drive to stop.
<>Off Bit 10 = 1, Control Word valid The drive will continue with the previous sen d valid
Control word and spee d reference until the timer
programmed in P 803 expires. Aft er th at th e drive
will do the action programmed in P 804.
The drive leaves the Clear Reaction STate when the
master sends process data values <> 0.
NB!:
The behaviour, which is described in the first
line is the factory setting. In critical applications
a time out function can be used. In case
of clear mode, the drive is working as described
in the selection of parameter 805.
MG.90.A5.02 - VLT is a registered Danfoss trademark
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