Endress+Hauser PROline Prosonic Flow 93 Function Manual page 182

5 Discrete Output function block
182
Signal processing in the RCAS (remote cascade operation) operating mode is largely
identical to the CAS operating mode. However, in this operating mode, control of the
SP_D parameter does not take place via an upstream function block but rather via a
fieldbus host system. The output value and status of the Discrete Output function block
is communicated to the fieldbus host system as a feedback message via the
RCAS_OUT_D parameter.
In the AUTO (automatic) operating mode, the setpoint value (SP_D parameter) is
prescribed directly in the Discrete Output function block. In this case, the CAS_IN_D
parameter is not taken into consideration in the internal calculation.
In the MAN (manual) operating mode, the output value (OUT_D parameter) can be
prescribed directly in the Discrete Output function block. No internal calculation takes
place.
The most important functions and parameters of the Discrete Output function block are
listed below; you will find an overview of all the parameters available on Page 184 ff.
5.2 Selecting the operating mode
The operating mode is set by means of the MODE_BLK parameter group,
(see Page 187). The Discrete Output function block supports the following operating
modes:
– AUTO
– MAN
– CAS
– RCAS
– OOS
5.3 Security behaviour
There is a safety default available (fault state) for the Discrete Output function block.
This is activated when a fault condition (of the corresponding valid setpoint value) exists
longer than defined in the FSTATE_TIME parameter, or when the SET_FSTATE parameter
in the Resource Block is activated. The security behaviour is determined via the
FSTATE_TIME, FSTATE_VAL_D, and IO_OPTS parameters.
5.4 Assignment: DO function block/Transducer Blocks
The Discrete Output function block and the Transducer Blocks are assigned/connected
via the CHANNEL parameter,
(option "16" → Discrete Output function block).
5.5 Values for the CAS_IN_D, RCAS_IN_D, OUT_D, and
SP_D parameters
Via the Discrete Output function block, different instrument functions in the appropriate
Transducer Blocks can be initiated via manufacturer-specific, fixed setpoint values from
an upstream function block.
Here it must be observed that the desired function is only then executed when a status
change from the value 0 (Discrete state 0) to the corresponding function value takes
place (see Table). The value 0 always serves as the starting point for the corresponding
control of instrument functions. A status change from a value not equal to zero to another
value has no effect.
PROline Prosonic Flow 93 FOUNDATION Fieldbus
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