Scheduled Events

From SysCAD Documentation

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

Contents 1 General Description 1.1 Diagram 2 Inputs and Outputs 3 Data Sections 4 Adding this Model to a Project

General Description

This model is used in Dynamic Simulation only.

The Scheduled Events unit operation can be used to simulate downtime of a piece of equipment due to a scheduled event such as maintenance or plant shutdown. The model allows one tag to be set to different values depending on whether the unit is active or inactive due to a scheduled event.

Diagram

The diagram shows the default drawing of the Scheduled Events unit.

Inputs and Outputs

There are no connections to this unit.

Data Sections

The default sections and variable names are described in detail in the following tables. The default Scheduled Events access window consists of 2 sections. This number may increase or decrease, based on user configuration.

1. The first section, which has the same name ScheduledEvents, contains general information relating to the unit
2. The second section, Info, contains general information.

Class: ScheduledEvents - The first tab page in the access window will have this name.

Tag / Symbol	Input / Calc	Description/Calculated Variables / Options
Common First Data Section
On	Tick box	Switch the unit on (ticked) or off (cleared).
SetTagAlways	Tick box	If not ticked, the model will only set the output tag for first iteration and when the value changes. Therefore if the user or another controller changes the same tag it will not be overwritten by this model until the next event occurs. If ticked the model will set the output tag every iteration.
IntegralPeriod	Tick box	This relates to the active period of the unit between scheduled events. If this box is ticked, then SysCAD may adjust the active period entered to suit the stepsize of the project. For example, if the step size is 1 hour, and the period given is not an exact number of hours, then SysCAD will adjust this number to make it an exact number of hours. If this box is left clear, then SysCAD will use the exact number entered. This may lead to some unevenness in the periods but the total amount of active time will be correct over a long period of time.
IntegralInactivePeriod	Tick box	This is the same as IntegralPeriod except it relates to the inactive period of the unit due to the scheduled event. If this box is ticked, then SysCAD may adjust the inactive period entered to suit the stepsize of the project. If this box is left clear, then SysCAD will use the exact number entered. This may lead to some unevenness in the periods but the total amount of inactive time will be correct over a long period of time.
Count	Input	The number of independent scheduled event blocks required. This may be any number from 0 up to 20. The user may also change this number at any time except when the model is running. The unit will always add new downtime blocks after existing ones, and it will delete them starting from the last block. E.g. if you have 5 scheduled event blocks set up and you change this to 4, scheduled event block number 5 will be deleted.
Reset_All	Button	This will reset the results values and restart any offsets.
Each independent scheduled event block has the following layout. Additional tab pages will be added as required to fit more scheduled event blocks.
SE.[Scheduled Event Block number]
Requirements...
Desc	Input	Optional scheduled event block description.
RqdPeriod	Input	Required Period - The total time period from the start of one scheduled event to the start of the next scheduled event.
Offset	Input	The time period before the first scheduled event will occur. The offset can be larger than the Period to effectively allow the output remain active until the scheduled period. The output will be active during the offset period. This time is reset if the reset button is pressed.
RqdInactivePeriod	Input	Required Inactive Period - The time period of the downtime due to the scheduled event, i.e. how long the equipment is inactive. This must be less than or equal to the Period. If it is equal to the period, the output will always be the inactive value (i.e. it is always inactive).
ActiveVal	Input	The value used for Output. If a TagToSet has a valid tag, then that tag will have this value when the equipment is active (i.e. not stopped) due to the scheduled event.
InactiveVal	Input	The value used for Output. If a TagToSet has a valid tag, then that tag will have this value when the equipment is inactive (i.e. stopped) due to the scheduled event.
TagToSet	Input	This input is optional. The tag to be set when the equipment is active or inactive (values as defined above) due to the scheduled event. The current value being set is shown in Output.
Results...
Period	Output	The total time period from the start of one scheduled event to the start of the next scheduled event. This may be different to the number entered if the IntegralPeriod option has been selected.
ActivePeriod	Output	This is equal to Period - InactivePeriod. It is the time the equipment is active due to the scheduled event.
InactivePeriod	Output	The time period of the downtime due to the scheduled event, i.e. how long the equipment is inactive. This may be slightly different to the number entered if the IntegralInactivePeriod option has been selected.
Active	Output	The current state of the equipment, expressed as a numerical value. This value could be referenced in PGMs for example to perform a series of tasks depending on the state of the equipment. If the equipment is active, then the value is 1. If the equipment is inactive due to the scheduled event then the value is 0.
Output	Output	The value that TagToSet is set to (if specified).
TtlInactiveTime	Output	The total amount of inactive time due to the scheduled event since the model was last reset.
TimeToNextInactivePeriod	Output	The amount of time until the next inactive period due to the scheduled event.
NextEvent	Output	The time and date of the next scheduled event.

Adding this Model to a Project

Insert into Configuration file

Sort either by DLL or Group.

	DLL:	Control1.dll	→	Units/Links	→	Control: Scheduled Events
or	Group:	General	→	Units/Links	→	Control: Scheduled Events

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

Insert into Project

Insert Unit

→

Control

→

Scheduled Events

See Insert Unit for general information on inserting units.