VGEN (FB)

The 'VGEN' function block is a velocity generator.
The output value is a position setpoint which changes in proportion with the velocity. It is also possible to output a defined number of increments.

The following functions are supported:

Generation of an increment increase in accordance with a definable velocity.
Online changes to input parameters
Modes for continuous and cyclic increment generation

Abbildung 23: VGEN: Block diagram

User interface

Input variables

Name

Type

Description

boEnable

BOOL

Enable signal: With a positive edge, the initialisation of the block starts.

As long as 'boEnable' = TRUE, the block remains enabled and is processed by the PLC.

In the state 'boEnable' = FALSE the block is no longer enabled and is thus no longer processed.

boControl

BOOL

Start / Stop

Range		Meaning
enMode = VGEN_CONT	FALSE	Velocity = 0
enMode = VGEN_CONT	TRUE	Velocity = 'diVelocity'
enMode = VGEN_CYCLE	FALSE -> TRUE	Velocity = 'diVelocity' for a series of 'udModPos' increments

enMode

ENUM

EN_VGEN_MODE

Selection mode of the operating mode

Default

VGEN_CONT

Range	Meaning
VGEN_CONT	Continuous increment increase, as long as 'boControl' = TRUE
VGEN_CYCLE	Increment increase by the defined value 'udModPos' on a positive edge at 'boControl'

diVelocity

DINT

Setpoint velocity

Definition of the final velocity

Range	-300000000 ... 300000000
Unit	incr/s
Default	1000

udModPos

UDINT

Modulo position

Number of increments to be output in mode 'enMode' = VGEN_CYCLE

Unit	incr
Default	2000

siOverride

SINT

Velocity output factor

Range	-100 ... +100
Unit	%
Default	100

Output variables

Name

Type

Description

boEnabAck

BOOL

Acknowledgement: Function block is initialised and enabled

boErr

BOOL

The function block is in an error state

FALSE	No error (permitted commanding or warning)
TRUE	Error

iErrID

INT

Error identity number: Diagnostic number is output

iErrID = 0		No error
iErrID ≠ 0	boErr = TRUE	Error
iErrID ≠ 0	boErr = FALSE	Warning

Warning

Range	Meaning
1	Illegal mode

Error

Range	Meaning
1	Illegal setpoint velocity (limited to minimum or maximum value)
2	Illegal override (limited to minimum or maximum value)

boSetVel

BOOL

When 'boSetVel' is active, the target velocity has been reached.

diOutVal

DINT

Output value

Input and output variables
Name	Type	Description
stDevice	STRUCT	The device description structure assigns the block a device.

Description

Abbildung 24: VGEN: Principle of operation

'enMode' is used to differentiate between continuous and cyclic operation.

Continuous operation: 'enMode' = VGEN_CONT
Generation of a continuous increment increase, corresponding to a predefined setpoint velocity ('diVelocity' [incr/s]). The increment increase is controlled with the control signal ('boControl').
'boControl' = TRUE
t1 ≤ t ≤ t2; t3 < t
'boControl' = FALSE
t < t1; t2 ≤ t ≤ t3
Cyclic operation: 'enMode' = VGEN_CYCLE
Generation of a defined increment increase ('udModPos' [incr]) corresponding to a predefined setpoint velocity ('diVelocity' [incr/s]). The increment increase is controlled with the positive edge of the control signal ('boControl').
'boControl' =FALSE -> TRUE (t = t1; t = t3):
Increment increase udModPos
t1 ≤ t ≤ t2; t3 ≤ t ≤ t4

'boControl' = TRUE	t1 ≤ t ≤ t2; t3 < t
'boControl' = FALSE	t < t1; t2 ≤ t ≤ t3