LGF_Integration (FB / 3.1.0)

Author: Siemens Digital Industries

Short description

The function approximately calculates the area under a function curve (the integral). The function curve is transferred as an analog value (LReal) which varies over time. The integral value is output on integral.
The implementation is based on the trapezoidal rule and uses second [s] as time base, e.g. speed [m/s].

Block Interface


Bool	enable	integral	LReal
Bool	enable	integral	LReal
LReal	value	error	Bool
LReal	value	error	Bool
Bool	reset	status	Word
Bool	reset	status	Word
		subfunctionStatus	Word
		subfunctionStatus	Word

Input parameter

Identifier	Data type	Default value	Description
enable	Bool	FALSE	Enables integral calculation If this input is set to the value `FALSE`, the integral calculation is stopped and the `integral` output shows the last calculated value.
value	LReal	0.0	Analog value of the continuous function curve, based on [s], (e.g. [volume flow/s])
reset	Bool	FALSE	Sets the output “integral” to “0.0”.

Output parameter

Identifier	Data type	Description
integral	LReal	Integral value
error	Bool	FALSE: No error 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 (see following Table)
subfunctionStatus	Word	Status or return value of called FB's, FC's and system blocks

Status & Error codes

Code / Value	Identifier / Description
16#0000	STATUS_EXECUTION_FINISHED_NO_ERROR Status: No error in the function during execution
16#8600	ERR_READ_SYS_TIME Error: System time FC `RD_SYS_T` returned an error when excuting - check `subFunctionStatus` code

Functional description

NOTE: The status of called commands is output in subFunctionStatus. In this case, the output value in status indicates which command caused the error. In this case, refer to the TIA Portal Online Help section for information on the respective commands.

The integral calculation includes the summation of those trapezoidal areas that span between the last two function values on the value input and the time. The elapsed time is calculated via the system time of the CPU. This trapezoidal area is identical to the product of the mean value of the two process values and the time interval.

NOTE: The calculation takes [s] as time base. So the analoge value hase to use the same time base, e.g. speed [m/s].

A = \frac{1}{2} * (F_{t_1}+F_{t_0}) * (t_1-t_0) + \frac{1}{2} * (F_{t_2}+F_{t_1}) * (t_2-t_1) + ...

Figure: Principle of operation

LGF_Integration - Principle of operation

Start the integral calculation for the inputvalue at the parameter value:

Set the parameter enable to the value TRUE
Set the parameter reset to the value FALSE

If the parameter enable is set to the value FALSE, the integral calculation is stopped and the output integral outputs the last calculated value.
If the parameter reset is set to the value TRUE, the output integral is reset to 0.0

Change log

Version & Date		Change description
	1.0.0	Siemens Industry Online Support
	17.02.2017	First released version
	1.0.1	Siemens Industry Online Support
	17.08.2018	Upgrade: TIA V15 Update 2
	1.0.2	Siemens Industry Online Support
	23.11.2018	Upgrade: TIA V15.1
	1.1.0	Simatic Systems Support
	12.11.2019	Regions, comments and constants are added, code refactored
	3.0.0	Simatic Systems Support
	23.04.2020	Set version to V3.0.0, harmonize the version of the whole library
	3.0.1	Simatic Systems Support
	09.02.2021	Insert documentation
	3.0.2	Simatic Systems Support
	07.06.2021	Fix bug - incompatibility with S7-1200 and LTIME
	3.1.0	Simatic Systems Support
	11.07.2025	Fix bug - Time measurement and calculation for nanoseconds fixed Fix Wording/Bug - Time measurement scaling [ms] / [s] - timing for calculatiuon is bnased on seconds