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Multi-Input/Output Device
Parameterization and Operation
Actuator Drive Design with Act. Fail Action Parameter
The MIO device supports the 2 most frequent valve drive designs "self-opening" and "self-
closing". For choosing between these 2 options, the actuator drive and the control actuators
must be considered a unit. Self-opening and self-closing designate the behavior of the drive
when setting the electrical control system to "0". This is independent of the behavior of the
drive during a failure of the auxiliary power. The following values can be set:
Undefined
■
Self-opening
■
Self-closing
■
The value "undefined" is the default setting at the time of delivery. Setting the valve drive to a
defined state is required for the configuration of the MIO device. The transducer block leaves
the mode "Out of Service" only if 1 of the 2 options "self-opening" or "self-closing" is set.
Depending on the setting of the Act. Fail Action parameter, the transducer block determines
whether or not the connected auxiliary valve must be controlled electrically for starting a
position set by the function block.
Controlling a double-acting drive requires 2 channels, i. e., 2 DO function blocks and
2 transducer blocks.
4.5.3
Final Position Feedback
This section describes the options for parameterizing the final position feedback contact.
Prerequisite: Ensure that the Act. Fail Action parameter has a value assigned for the design of
the valve drive.
The response of the final position feedback contact is influenced by the following 2 parameters:
Sensor Usage parameter: Describes whether a final position feedback contact is
■
connected to the MIO device and how to evaluate its signals.
PV_D Generation parameter: If the signals of the final position feedback contacts are
■
evaluated, this parameter determines how to further process the evaluated signals prior to
transferring them to the function block.
Sensor Usage Parameter
The following settings are possible:
No position detection
■
Use sensor values for the Primary Value
■
Use options A ... D to determine the Sensor Usage parameter
■
No position detection
No final position feedback contact is connected to the MIO device. The current reference value
is returned as valve position to the function block.
Use sensor values for the Primary Value parameter
The 2 signals of the final position feedback contacts are transferred to the function block
without evaluation. The 2 binary signals are represented on bit 0 (position feedback contact A)
and bit 1 (position feedback contact B). Here, numerical values can be generated from 0 ... 3.
Possible problems are described in the next section PV_D Generation parameter.
Observe that the MIO device interprets a final position feedback contact signal as follows:
High current => logical 1
Low current => logical 0
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