FB_CTRL_MULTIPLE_PWM_OUT

FB_CTRL_MULTIPLE_PWM_OUT 1:

This function block creates PWM modulated output signals from a number of input signals in such a way that the temporal relationships between the output signals are arranged so that as few outputs as possible are switched on at any one time. This temporal arrangement reduces the maximum power necessary required for the actuators.

Both the minimum switch-on time and the minimum switch-off time can be parameterized, in addition to the mark-to-space ratio, in this extended function block.

Description of the output behavior 1

FB_CTRL_MULTIPLE_PWM_OUT 2:

Description of the output behavior 2

FB_CTRL_MULTIPLE_PWM_OUT 3:

The programmer must create the following arrays in the PLC if this function block is to be used:

aPwmInput           : ARRAY[1..nNumPwmOut] OF FLOAT;
aStWaitTimesConfig  : ARRAY[1..nNumPwmOut] OF ST_CTRL_MULTIPLE_PWM_OUT_TIMES;
aStPwmOutputs       : ARRAY[1.. nNumPwmOut] OF ST_CTRL_MULTIPLE_PWM_OUT_OUTPUTS;
aStPwmDataVars      : ARRAY[1.. nNumPwmOut] OF ST_CTRL_MULTIPLE_PWM_OUT_DATA;

The input values for the individual channels of the PWM function block are written into the ar_fPwmInput array. The programmer can specify the parameterizable times for the individual channels in the ar_stWaitTimesConfig array. The function block writes the output bits into the ar_stPwmOutputs array. The internal data required by the function block is stored in the ar_stPwmDataVars array. Under no circumstances should the structures contained in the array ar_stPwmDataVars be changed within the PLC program. This procedure is also illustrated in the sample program listed below.

VAR_INPUT

VAR_INPUT
    eMode    : E_CTRL_MODE;
END_VAR

Name	Type	Description
eMode	E_CTRL_MODE	Input that specifies the operation mode of the function block.

VAR_OUTPUT

VAR_OUTPUT
    eState    : E_CTRL_STATE;
    bError    : BOOL;
    eErrorId  : E_CTRL_ERRORCODES;
END_VAR

Name	Type	Description
eState	E_CTRL_STATE	State of the function block
bError	BOOL	Supplies the error number when the output `bError` is set.
eErrorId	E_CTRL_ERRORCODES	Becomes TRUE, as soon as an error occurs.

VAR_IN_OUT

VAR_IN_OUT
    stParams    : ST_CTRL_PWM_OUT_EXT_PARAMS;
END_VAR

Name	Type	Description
stParams	ST_CTRL_PWM_OUT_EXT_ PARAMS	Parameter structure of the PWM element

stParams consists of the following elements:

TYPE ST_CTRL_MULTIPLE_PWM_OUT_PARAMS :
STRUCT
    tTaskCycleTime            : TIME;
    tPWMPeriod                : TIME; 
    nNumberOfPwmOutputs       : USINT;
    pPwmInputArray_ADR        : POINTER TO FLOAT := 0;
    nPwmInputArray_SIZEOF     : UINT;
    pPwmTimesConfig_ADR       : POINTER TO ST_CTRL_MULTIPLE_PWM_OUT_TIMES;
    nPwmTimesConfig_SIZEOF    : UINT;
    pPwmOutputArray_ADR       : POINTER TO ST_CTRL_MULTIPLE_PWM_OUT_OUTPUTS;
    nPwmOutputArray_SIZEOF    : UINT;
    pPwmData_ADR              : POINTER TO ST_CTRL_MULTIPLE_PWM_OUT_DATA;
    nPwmData_SIZEOF           : UINT;
END_STRUCT
END_TYPE

Name	Type	Description
tTaskCycleTime	TIME	Cycle time with which the function block is called. If the function block is called in every cycle this corresponds to the task cycle time of the calling task.
tPWMPeriod	TIME	Period of the PWM signal
nNumberOfPwmOutputs	USINT	Number of PWM outputs. [1...n]
pPwmInputArray_ADR	POINTER TO FLOAT	Address of the PWM input array
nPwmInputArray_SIZEOF	UINT	Size of the PWM input array in bytes
pPwmTimesConfig_ADR	POINTER TO ST_CTRL_ MULTIPLE_PWM_OUT_TIMES	Address of the PWM times array
nPwmTimesConfig_SIZEOF	UINT	Size of the PWM times array in bytes
pPwmOutputArray_ADR	POINTER TO ST_CTRL_ MULTIPLE_PWM_OUT_OUTPUTS	Address of the PWM output array
nPwmOutputArray_SIZEOF	UINT	Size of the PWM output array in bytes
pPwmData_ADR	POINTER TO ST_CTRL_ MULTIPLE_PWM_OUT_DATA	Address of the internal PWM data array
nPwmData_SIZEOF	UINT	Size of the internal PWM data array in bytes

TYPE ST_CTRL_MULTIPLE_PWM_OUT_TIMES :
STRUCT
     tMinOnTime    : TIME;
    tMinOffTime   : TIME;
    tMinWaitTime  : TIME;
END_STRUCT
END_TYPE

Name	Type	Description
tMinOnTime	TIME	Minimum switch-on time of the PWM output
tMinOffTime	TIME	Minimum switch-off time of the PWM output
tMinWaitTime	TIME	Waiting time between the switching actions between a positive and negative output signal

TYPE ST_CTRL_MULTIPLE_PWM_OUT_OUTPUTS :
STRUCT
     bPwmOutBitPos    : BOOL;
     bPwmOutBitNeg    : BOOL;
     bWaitTimeActive  : BOOL;
END_STRUCT
END_TYPE

Name	Type	Description
bPwmOutBit Pos	BOOL	PWM signal, when fPwmInput > 0.0
bPwmOutBit Neg	BOOL	PWM signal, when fPwmInput < 0.0
bWaitTime Active	BOOL	A TRUE at this output indicates that the waiting time between the switching actions of the output signals is active. This output can be used to hold an I component that may be present in the prior controller constant during this time.

TYPE ST_CTRL_MULTIPLE_PWM_OUT_DATA :
STRUCT
 Internal structure. This must not be written to.
END_STRUCT
END_TYPE