Table of Contents

Two-stage Source (v2.0)

Full Name

Lib.Mervis.v2_0.TwoStageSource

Description

Block used for controlling the performance of a source (primarily a boiler with a modulated burner and a circulation pump).

Required Project References

Usage in ST

program test
    var
        twoStageBoiler: lib.mervis.v2_0.TwoStageSource;
    end_var

    twoStageBoiler();
end_program

Description of Inputs and Outputs

Inputs Name Data TypeRetainRequired Connection Meaning
OperatingMode Lib.Mervis.v1_0.OperatingModeTypeYes No Source operating mode
PumpOperatingMode Lib.Mervis.v1_0.OperatingModeTypeYes No Circulation pump operating mode
ManualPower real Yes No Source power in manual mode
Output real No Yes Controlled variable
Demand Lib.Mervis.v2_0.StageControlTypeNo Yes Combined demand from the cascade controller
Feedback bool No No Feedback signal of source operation
Failure bool No No Feedback signal of source failure
PumpFeedback bool No No Feedback signal of circulation pump operation
PumpFailure bool No No Feedback signal of circulation pump failure
ResetRuntime bool No No Reset runtime hours
MinimalOutput real No No External input for defining the minimum output temperature (if zero, it is not used)
LimitForAttach real No No Limit value of the criterion for activating the second stage
LimitForDettach real No No Limit value of the criterion for deactivating the second stage
MaxOutput real No No Maximum value of the controlled variable, exceeding it is considered a fault
FeedbackTimeout time No No Interval waiting for active source operation feedback
FailureCountLimit uint No No Number of consecutive source errors before it is permanently marked as non-functional
FailureDelay time No No Time after an unsuccessful source start before retrying
MinimalRunTime time No No Minimum time the source will be kept running
MinimalStopTime time No No Minimum time before the source is restarted
KeepCommandWhileFailure bool No No Determines whether the operation command remains active even in case of a fault
UseLocalOutput bool No No Determines whether the control uses the common output or its own (= true)
PumpRunDown time No No Run-down time of the circulation pump after the source is removed from the cascade
PumpFeedbackTimeout time No No Interval waiting for active circulation pump operation feedback
PumpNotRunAlarmPriority AlarmPriorityType No No Priority of the circulation pump not running fault
PumpFailureAlarmPriorityAlarmPriorityType No No Priority of the circulation pump failure
Outputs Name Data Type Meaning
State Lib.Mervis.v2_0.StageInfoTypeCombined source state to the cascade controller
Command1 bool Command for operating the first stage
Command2 bool Command for operating the second stage
PumpCommand bool Command for the circulation pump
RunTimeInHours udint Source runtime in whole hours
PumpCompositeStateudint Bit field describing the state of the circulation pump (see SwitcherBlock v2.0)
Blocks Name Data Type Meaning
PumpControl Lib.Mervis.v2_0.SwitcherBlockControl of the circulation pump
Alarms Lib.Mervis.v1_0.AlarmsExtender4 Alarm function block

Alarm InputPriorityMeaning
Alarm1 33 Source failure
Alarm2 - Not used
Alarm3 33 Exceeding maximum output value
Alarm4 - Not used

Detailed Function Description

TODO

Usage Example

Versions