Input and Output Signals
Publication PUB091-003-00_0119
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Digital Input DI-4
Applicable to IQ and IQT actuators only. This bit reports the status of
the contact connected to the actuator hard wired
ESD
terminals. The
input can be used to control the actuator or simply to report the status
of a plant feedback signal. The function is set in the Auxiliary Input
Mask parameter which determines whether the bit is reported as true
(1) for a closed contact or an open contact and whether the input
controls the actuator or not. Note that the input is always reported
even when it is also controlling the actuator.
A configuration feature also allows DI-4 to be set to act as a ‘Disable
Fieldbus Control’ input. In this mode when the input is made
(irrespective of the Auxiliary Mask setting) the actuator cannot be
controlled over the network. This can be useful during plant
commissioning to prevent unwanted valve movement.
5.2.3
Digital Inputs from IQT Actuator
Slow Mode
Applicable to IQT actuators only. In positioning mode, when the IQT
actuator approaches its setpoint the motor automatically switches to
‘slow mode’ and the actuator runs at a lower speed. This allows any
developed inertia to be dissipated and a better positional accuracy to
be achieved without overshoot. The deviation from the setpoint at
which slow mode is adopted is set in the associated parameter.
When slow mode is in use this bit will be true (1).
The IQ and Q actuators also report this bit, but these actuators do not
have a slow mode capability.
5.3 Actuator Analogue Input Feedback
The Modbus Module makes available over the network a number of analogue variables. These
contain information about the valve and actuator. If the single highway with analogue input variant of
the Modbus Module is used, one associated plant measurement is also available.
Analogue Feedback
IQ / IQT actuator
SI / EH actuator
ROMpak / Q actuator
Actuator Instantaneous Torque
Valve Position
Analogue Input
Note:
– Requires the Single H Analogue Input Modbus Module.
-
SI and EH actuators report hydraulic pressure instead of torque.
Torque
The currently developed torque value is reported as an Integer Value
in the range 0 to 120 (0-78 hex) representing the percentage of
actuator rated torque generated.
Valve Position
The current valve position is reported as an Integer Value in the range
0 to 1000 (0 – 3E8 hex) representing the percentage position to 0.1%
resolution.
The IQ and IQT actuator automatically scales the valve position value
reported from the setting of the limit switches.
The Q actuator requires the valve to be stroked fully between the
closed and open limit switches for the value to be automatically
