Installation, Operation and Maintenance Manual
MDE 254 Rev. 1 March 2021
Device Variables 47
Section 9: Device Variables
9.3 Device Variable 0: Commands
This variable permits to send a command to the actuator. It is a bit_enumerated variable; the possible
values are:
Table 136.
Bit Description Value
b0 Open Command ON = 1, OFF = 0
b1 Close Command ON = 1, OFF = 0
b2 Stop Command ON = 1, OFF = 0
b3 ESD / PST Command ON = 1, OFF = 0
b4 Enable Positioner ON = 1, OFF = 0
b5 Interlock Open Command ON = 1, OFF = 0
b6 Interlock Close Command ON = 1, OFF = 0
b7 - b31 Not Defined ON = 1, OFF = 0
Commands Open, Close, Stop, Enable Positioner of Device variable 0 work only in LOOP DISABLE mode
and Multidrop. The commands ESD/PST, Interlock Open and Interlock Close are always available.
In LOOP ENABLE mode the commands Open, Close, Stop, Enable Positioner are always cleared.
Open: the command sends an open command to actuator. The command is memorized in the HART
module interface and will be reset by Stop command or end of travel in opening.
Close: the command sends a close command to actuator. The command is memorized in the HART
module interface and will be reset by Stop command or end of travel in closing.
Stop: the command stops actuator movement.
Example of sequence of Open commands:
• Set Open command
• Clear open command
• Set Stop command to stop actuator in intermediate position
• Clear Stop command before setting a new Open or Close command
If both commands Open and Close are set the actuator stops.
ESD / PST Command: It generates an ESD / PST command to actuator and overrides any other
existing command (as the hardwired ESD does).
See “Appendix B.1 Multiple Functionality of ESD Command and Status” for details.
Enable Positioner: The command enables control of actuator by digital HART position request in the
range 0.0 - 100.0. The Open, Close, Stop commands are disabled.
Interlock Open Command: It inhibits the open movement (as the hardwired command does).
See “Appendix B.2 Multiple Functionality of Interlock Command” for details.
Interlock Close Command: It inhibit the close movement (as the hardwired command does).
See “Appendix B.2 Multiple Functionality of Interlock Command” for details.
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