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Navigation: Main Page -> Models -> Control 2 Models

General Description

The Actuator is used to get a value from a PID block and then change the value of a tag in the model. Its use is not required since a PID block can directly access tags. However, it can add value by better displaying the control logic on a flowsheet and representing the equipment in the field.



Model Theory

The actuator can be an orphan model; it need not be connected to any other unit operation.

The PID unit can be connected to an actuator by a control link. To connect, use the insert link function, and select the PID output value as the source and the actuator as the destination. When the connection is made, the PID output tag will be set to the actuator tag.

Note: The actuator output_tag must be a write-able field, eg. Feeder.Qm_Rqd.

Data Sections

Summary of Data Sections

  1. Actuator tab - Contains general information relating to the unit.
  2. Info tab - Contains general settings for the unit and allows the user to include documentation about the unit and create Hyperlinks to external documents.

Actuator Page

Unit Type: Actuator - The first tab page in the access window will have this name.

Tag (Long/Short) Input / Calc Description/Calculated Variables / Options
Tag Display This name tag may be modified with the change tag option.
Condition Display OK if no errors/warnings, otherwise lists errors/warnings.
ConditionCount Display The current number of errors/warnings. If condition is OK, returns 0.
GeneralDescription / GenDesc Display This is an automatically generated description for the unit. If the user has entered text in the 'EqpDesc' field on the Info tab (see below), this will be displayed here. If this field is blank, then:
  • For pipes, SysCAD will use the text in the 'ConnectDesc' field - this displays the Source and Destination tags of the pipe;
  • For Feeders/Cross Page Connectors, SysCAD will display the state of the unit, i.e. if it is a Feeder or a Sink, etc.;
  • For other units SysCAD will display the unit class ID.
On Tick Box All of the independent Actuators will be enabled or disabled using this box.
ShowCnv Tick Box  
Ac_Cnt/Count Input The number of independent Actuators required. The default is 1.
The user may also change this number at any time. However, the unit will always add new Actuator after existing ones, and it will delete them starting from the last Actuator.
E.g. if you have 5 Actuators set up and you change this to 4, Actuator number 5 will be deleted.
Check Tags Button SysCAD will perform a check on the validity of the tag(s).
State Output The state of the Actuator. If everything is correct and operating normally, the user will see OK in this box. Otherwise the unit will flag an error message, which helps the user to locate the problem with the controller.
MSG_1 to MSG_2 Output Any errors will be reported here. These messages are also displayed in the message window.
Each independent Actuator has the following layout. The first Actuator will be displayed on the first page. Each page thereafter displays multiple actuators.
Tag.Cfg.[Actuator number]
ID Input This will be the same name as the Output tag if not specified.
OutputTag Input The output variable, it must be a valid tag name and it must be write-able. The user may type the tag in, however it is preferable to use the cut and paste function to avoid any typing errors.
RequiredValue Output The output variable's value.

Note: The remaining variables are used in Dynamic simulations in conjunctions with control system testing. They have no significance in ProBal thus not documented.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.





Control 2: Actuator





Control 2: Actuator

See Project Configuration for more information on adding models to the configuration file.

Insert into Project


Insert Unit

Control 2


See Insert Unit for general information on inserting units.