Pakscan IIE System Manual
56 of 132
Publication S177E V2.0 Issue 03/05
8.8.4.1
Further Loop Options
1>Retain data on
Comms fail =OFF
2>IQ DV Convert=OFF
Two further settings for the data on the loop can be made from this screen.
There is an option to make the data held in the Modbus database for each FCU retain the last value
obtained prior to loss of communication with the field unit should this occur. Retaining the data (ON)
has the effect of reporting the last known position of the valve. The alternate option (OFF) is that once
communications is lost the data is cleared to all zeros. Clearing the data ensures that information
cannot falsely report actuator position data. The default value is OFF.
The IQ DV Convert option can be used to ensure that 100% and 0% Desired Value outputs to the IQ
actuators only is transformed into actions to make the actuator run to the fully open (100%) and fully
closed (0%) positions. With IQ DV Convert set to ON, the command message is converted from a DV
command to an Open or Close command. This is useful for positioning actuators where it is possible
that the valve will not fully shut or open when moved by only a small amount. When used for tight shut
off valves with analogue position control only the setting should be ON.
With IQ DV Convert set to OFF the DV command is not changed and the actuator positions to as near
to 0 and 100% as the deadband setting allows. If Limited Range Positioning is being used the setting
must be OFF. The default is OFF.
Commands available:
-
Toggle Retain Last Data setting
-
Toggle IQ DV Convert option
-
Return to previous menu
MENU
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