LGF_MeasureCpuLoad (FB / 1.1.1)

Author: Simatic Systems Support

Short description

Measurement and calculation of PLC CPU load for different OB types

Block Interface


Bool	enable	valid	Bool
Bool	enable	valid	Bool
Bool	reset	busy	Bool
Bool	reset	busy	Bool
Real	loadCascade	error	Bool
Real	loadCascade	error	Bool
LGF_typeMeasureCpuLoad_Configuration	configuration	status	Word
LGF_typeMeasureCpuLoad_Configuration	configuration	status	Word
		averagingActive	Bool
		averagingActive	Bool
		loadCascadeActive	Bool
		loadCascadeActive	Bool
		cycleTimeMin	LTime
		cycleTimeMin	LTime
		cycleTimeActual	LTime
		cycleTimeActual	LTime
		cycleTimeMax	LTime
		cycleTimeMax	LTime
		cycleTimeMaxConfigured	LTime
		cycleTimeMaxConfigured	LTime
		runtime	LReal
		runtime	LReal
		cpuLoad	Real
		cpuLoad	Real
		comLoad	Real
		comLoad	Real
		comLoadConfigured	Real
		comLoadConfigured	Real
		limitWarning	Bool
		limitWarning	Bool
		limitAlarm	Bool
		limitAlarm	Bool
		resultsCyclic	Array[0..#LAST_CYCLIC_BLOCK_INDEX] of LGF_typeMeasureCpuLoad_ResultBlock
		resultsCyclic
		results	Array[0..#LAST_BLOCK_INDEX] of LGF_typeMeasureCpuLoad_ResultBlock
		results
		diagnostics	LGF_typeDiagnostics
		diagnostics	LGF_typeDiagnostics

Input parameter

Identifier	Data type	Default value	Description
enable	Bool	FALSE	TRUE: Enable functionality of FB
reset	Bool	FALSE	Rising edge: Reset all internal values and as well PLC CPU timing statistic
loadCascade	Real	0.0	Percentage Load Value from another `LGF_MeasureCpuLoad` [%] (Connect `cpuLoad` from predecessor instance call)
configuration	LGF_typeMeasureCpuLoad_Configuration	---	This UDT belongs to the Module `LGF_MeasureCpuLoad` and lists all possible parameter to configure its behavior.

Output parameter

Identifier	Data type	Description
valid	Bool	TRUE: Valid set of output values available at the FB
busy	Bool	TRUE: FB is not finished, and new output values can be expected
error	Bool	TRUE: An error occurred during the execution of the FB
status	Word	16#0000 - 16#7FFF: Status of the FB, 16#8000 - 16#FFFF: Error identification
averagingActive	Bool	TRUE: Averaging of actual values active
loadCascadeActive	Bool	TRUE: Load calculation cascade active
cycleTimeMin	LTime	Minimum cycle time [ms]
cycleTimeActual	LTime	Actual cycle time [ms]
cycleTimeMax	LTime	Maximum cycle time [ms]
cycleTimeMaxConfigured	LTime	Configured maximum cycle time [ms] (in plc hardware configuration)
runtime	LReal	Actual cycle time incl. interrupts [ms]
cpuLoad	Real	Actual PLC CPU load [%]
comLoad	Real	Actual communication load [%]
comLoadConfigured	Real	Configured communication load [%]
limitWarning	Bool	Load more than configured threshold value 'configuration.limitWarning'
limitAlarm	Bool	Load more than configured threshold value 'configuration.limitAlarm'
resultsCyclic	Array[0..#LAST_CYCLIC_BLOCK_INDEX] of LGF_typeMeasureCpuLoad_ResultBlock	Results of Cyclic OB read outs
results	Array[0..#LAST_BLOCK_INDEX] of LGF_typeMeasureCpuLoad_ResultBlock	Results of NON-Cyclic OB read outs
diagnostics	LGF_typeDiagnostics	Diagnostic structure to store and transfer diagnostic information from blocks through the interface.

Status & Error codes

Code / Value	Identifier / Description
16#7000	STATUS_NO_CALL No job being currently processed
16#7001	STATUS_FIRST_CALL First call after incoming new job (rising edge 'enable')
16#7002	STATUS_SUBSEQUENT_CALL Subsequent call during active processing without further details
16#8600	ERR_UNDEFINED_STATE Error: Due to an undefined state in state machine
16#8601	ERROR_RTINFO_CONFIGURED_MAX_CYCLETIME Error: RT INFO read configured MAX cycle time Information
16#8602	ERROR_RTINFO_CONFIGURED_COM_LOAD Error: RT INFO read configured COM Load Information
16#8610	ERROR_RTINFO_ACTUAL_CYCLETIME Error: RT INFO read actual cycle time Information
16#8611	ERROR_RTINFO_ACTUAL_MIN_CYCLETIME Error: RT INFO read MIN cycle time Information
16#8612	ERROR_RTINFO_ACTUAL_MAX_CYCLETIME Error: RT INFO read MAX cycle time Information
16#8620	ERROR_RTINFO_ACTUAL_COM_LOAD Error: RT INFO read actual COM Load Information
16#8630	ERROR_RTINFO_RESET_STATISTICS Error: RT INFO reset statistic information
16#9000	ERROR_RTINFO_RUNTIME_OB_CYCLIC Error: Read RT INFO cycle time Information OB + index of OB in array
16#9100	ERROR_RTINFO_RUNTIME_OB Error: Read RT INFO cycle time Information OB + index of OB in array

User defined datatype(s)

LGF_typeMeasureCpuLoad_Configuration (UDT / V1.0.0)

This UDT belongs to the Module LGF_MeasureCpuLoad and lists all possible parameter to configure its behavior.

Identifier	Data type	Default value	Description
cfcRun	Bool	FALSE	CFC Run (OB No is shifted to 10xx)
averagingValues	USInt	0	Averaging the measured values by building the arithmetic average value
comLoadSim	UInt	0	Com Load Simulation [%] IF > 0.0 used as value for calculation IF <= 0.0 take real com load value read from PLC
limitWarning	Real	70.0	Warning threshold value [%]
limitAlarm	Real	100.0	Alarming threshold value [%]
organizationBlocksCyclic	Array[0..10] of LGF_typeMeasureCpuLoad_ConfigurationBlock	---	Cyclic Blocks to measure
organizationBlocks	Array[0..30] of LGF_typeMeasureCpuLoad_ConfigurationBlock	---	NON-Cyclic Blocks to measure

LGF_typeMeasureCpuLoad_ConfigurationBlock (UDT / V1.0.0)

Configuration for the block to be measured

Identifier	Data type	Default value	Description
enableMeasurement	Bool	FALSE	Enable measurement
obNumber	Int	0	Organization's Block Number of the module to be measured
initialLoad	Real	0.0	Initial load [%], only used if averaging is turned on

LGF_typeMeasureCpuLoad_ResultBlock (UDT / V1.0.0)

Results for Block measured

Identifier	Data type	Default value	Description
obNumber	Int	0	Organisation Block Number
runtime	LTime	---	Runtime of Organization block [ms]
cycleLoad	Real	0.0	Load of block calculated using the cycle time [%]
maxCycleLoad	Real	0.0	Load of block calculated using the MAX cycle time [%]
error	Bool	FALSE	TRUE: An error occurred during reading block statistic
status	Word	16#0000	16#0000 - 16#7FFF: Status of the `RT_INFO`, 16#8000 - 16#FFFF: Error identification

LGF_typeDiagnostics (UDT / V1.0.1)

Diagnostic structure to store and transfer diagnostic information from blocks through the interface.

Identifier	Data type	Default value	Description
status	Word	16#0000	Status of the Block or error identification when error occurred
subfunctionStatus	Word	16#0000	Status or return value of called FB's, FC's and system blocks
stateNumber	DInt	0	State in the state machine of the block where the error occurred

Functional description

This function can be used to read out the various runtimes of organizational blocks (OB) and calculate the PLC CPU load based on the results.

The OBs to be considered are specified and activated in the configuration; please note that cyclical and acyclically OBs must be configured in separate structures.

It is also possible to

Average/smooth the measured values
Specify limit values for a warning and an alarm
Specify the communication load as a simulated value
Automatically increment the OB numbers for CFC

Change log

Version & Date		Change description
	1.0.0	SAG BG
	19.05.2024	First Release
	1.1.0	SAG BG
	06.05.2024	Add Output with overall runtime incl. interrupts
	1.1.1	Siemens System Support
	03.09.2025	Bugfixed error in loop