L_USPP_Compare

This function block compares two signals of the "LREAL" data type and can for instance be used to implement a trigger.

The comparison operation is selected via the dwFunction input.

		L_USPP_Compare
LREAL	-	lrIn1	xOut	-	BOOL
LREAL	-	lrIn2	xError	-	BOOL
DWORD	-	dwFunction	eErrorID	-	L_IE1P_Error
LREAL	-	lrTolerance
LREAL	-	lrHysteresis

Inputs

Name Data type	Information/possible settings
lrIn1 LREAL	Input signal 1
lrIn2 LREAL	Input signal 2
dwFunction DWORD	Comparison operation
	0	lrIn1 = lrIn2 (initialisation)
	1	lrIn1 > lrIn2
	2	lrIn1 < lrIn2
	3	\|lrIn1\| = \|lrIn2\|
	4	\|lrIn1\| > \|lrIn2\|
	5	\|lrIn1\| < \|lrIn2\|
lrTolerance LREAL	Window for comparison operation Value is limited internally to ³ 0.
lrHysteresis LREAL	Hysteresis for comparison operation Value is limited internally to ³ 0.

Outputs

Name Data type	Value/meaning
xOut BOOL	TRUE	The statement of the selected comparison mode is true.
xError BOOL	TRUE	An error has occurred. For details see eErrorID .
eErrorID L_IE1P_Error	If xError = TRUE: Error number for the error that has occurred.

Name

Data type

Value/meaning

xOut

BOOL

TRUE

The statement of the selected comparison mode is true.

xError

BOOL

TRUE

An error has occurred. For details see eErrorID .

eErrorID

L_IE1P_Error

If xError = TRUE: Error number for the error that has occurred.

Comparison operation "lrIn1 = lrIn2"

Selection: dwFunction = 0

This function compares two signals with regard to equality. It can, for instance, provide the comparison "actual speed equals setpoint speed" (n _act = n _set ).

Use the input lrTolerance to select the window within which the equality is to apply.

Use the lrHysteresis input to select a hysteresis if the input signals are not stable and the output is therefore oscillating.

Switching performance lrIn1 = lrIn2

With this function, use the FB in a fast task to achieve optimum sampling of the signals.

Example lrIn1 = lrIn2

Comparison operation "lrIn1 > lrIn2"

Selection: dwFunction = 1

This function serves, for instance, to implement the comparison "actual speed is higher than a limit value" (n _act > n _x ) for one direction of rotation.

Switching performance lrIn1 > lrIn2

Function sequence:

If the value at lrIn1 exceeds the value at lrIn2 , xOut changes from FALSE to TRUE.

Only when the signal at lrIn1 falls below the value of lrIn2 - lrHysteresis again, xOut changes back from TRUE to FALSE.

Example lrIn1 > lrIn2

Comparison operation "lrIn1 < lrIn2"

Selection: dwFunction = 2

This function serves, for instance, to implement the comparison "actual speed is lower than a limit value" (n _act < n _x ) for one direction of rotation.

Switching performance lrIn1 < lrIn2

Function sequence:

1. If the value at lrIn1 falls below the value at lrIn2 , xOut changes from FALSE to TRUE.

Only when the signal at lrIn1 exceeds the value of lrIn2 - lrHysteresis again xOut changes back from TRUE to FALSE.

Example lrIn1 < lrIn2

Comparison operation |lrIn1| = |lrIn2|

Selection: dwFunction = 3

This function serves, for instance, to implement the comparison "actual speed equals zero" (n _act = 0).

This function behaves just like the "lrIn1 = lrIn2" comparison operation; however, the amount is generated by the input signals before signal processing (without sign).

Comparison operation |lrIn1| > |lrIn2|

Selection: dwFunction = 4

This function serves, for instance, to implement the comparison "actual speed is higher than a limit value" (|n _act | > |n _x |), irrespective of the direction of rotation.

This function behaves just like the "lrIn1 > lrIn2" comparison operation; however, the amount is generated by the input signals before signal processing (without sign).

Comparison operation |lrIn1| < |lrIn2|

Selection: dwFunction = 5

This function serves, for instance, to implement the comparison "actual speed is lower than a limit value" (|n _act | < |n _x |), irrespective of the direction of rotation.

This function behaves just like the "lrIn1 < lrIn2" comparison operation; however, the amount is generated by the input signals before signal processing (without sign).