Samson 4785, Монтаж и эксплуатация

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Operating modes of the transducer block
Out of Service (OS)
In this operating mode, the correction value received from the AO Function Block is not used.
The control valve is moved to the fail-safe position determined via ACT_FAIL_ACTION. The
positioner also switches to operating mode OS when the forced venting function has been ac-
tivated.
Automatic (Auto)
In this operating mode, the correction value received from the AO Function Block is used to
calculate a position value. The valve is positioned accordingly.
7.5.1 Start-up (warm start)
The response of the positioner to a warm start is determined by the parameter FSAFE_TYPE
(fail-safe action).
If FSAFE_TYPE is set to "adjust to fail-safe value", the positioner switches to automatic opera-
ting mode and adjusts to the value determined by the parameter FSAFE_VALUE.
If FSAFE_TYPE is set to "adjust to last set point value" or "fail-safe position determined by
spring action", the device remains in fail-safe position. As soon as a valid set point SP is
transmitted to the positioner, the operating mode changes to automatic.
If the status of the transmitted set point is "bad" or the positioner has not been successfully in-
itialized, it remains in fail-safe position (out of service).
7.5.2 Monitoring function FSAFE_TIME, FSAFE_TYPE, FSAFE _VALUE
The action determined by the parameter FSAFE_TYPE (fail-safe action) is triggered by the fol-
lowing events:
Start-up (warm start) of the positioner.
Elapsing of the DP watchdog through interruption of the cyclic communication with a Mas-
ter Class 1 (not applicable when communication is terminated properly).
In Automatic or Remote Cascade operating mode, when the status of the reference vari-
able SP or RCAS_IN valid in this operating mode is set to "Initiate Fail Safe". In this case,
the action determined by FSAFE_TYPE (fail-safe action) is triggered before the fail-safe
time has elapsed.
Receipt of a DP "Global Control" service for which the clear bit is set.
Setting the status of the reference variable valid in current operating mode to "bad".
EB 8382-2 EN
47
How to implement the PROFIBUS Master Class 1