3724 PWFM

Epec Programming and Libraries Manual

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3720/3724 PWFM

Even though the control properties can be set very accurately, the hardware limits the accuracy of the measured signal of the output pin.

PWFM channels are provided to the application as software channels 1...X. The software channel number is needed when the access function IO_PWFM_SET_CONFIG (FUN) is called.

The channel numbers are listed in section 3724 PLCopen Addresses / 3720 PLCopen Addresses.

Code examples

Disabled

PWFM channels are disabled by default.

To disable the channel, set the pwfmMode as follows:

Name	Area	Data Type	Range	Description
pwfmMode	Config	ENUM	IO_MODE_DISABLED	Used mode.
pwfmChn	Config	WORD	1-24	Configured channel.

Definitions:

error: WORD;

Init:

error := IO_PWFM_SET_CONFIG(i_PwfmMode:=IO_MODE_DISABLED,i_PwfmChn:=1);

IF error <> 0 THEN

(*error*)

;

END_IF

Digital Output

When the channel is used as digital output, the state of the output is set with the variable DoState.

Name	Area	Data Type	Range	Description
DoState	%Q	BOOL	TRUE/FALSE
pwfmMode	Config	ENUM	IO_PWFM_MODE_DIGITAL_OUTPUT	Used mode.
pwfmChn	Config	WORD	1-24	Configured channel.

Definitions:

error: WORD;

o_PwfmChn1_DoState AT %QX16.0:BOOL;

Init:

error := IO_PWFM_SET_CONFIG(i_PwfmMode:=IO_PWFM_MODE_DIGITAL_OUTPUT,i_PwfmChn:=1);

IF error <> 0 THEN

(*error*)

;

END_IF

Run:

(* Change DO state every application cycle. *)

if o_PwfmChn1_DoState then

o_PwfmChn1_DoState := FALSE;

else

o_PwfmChn1_DoState := TRUE;

end_if

Direct PWFM

When the channel is used as direct PWFM, the ratio and frequency of the output can be set freely.

PWM frequencies can be configured under software control in groups of outputs.

The setting is done by a PWM channel, setting the frequency of one channel sets also the frequencies of all the other channels in the same group.
The groups are indicated with the same PWM frequency channel number in section 3724 PLCopen Addresses / 3720 PLCopen Addresses.

Name	Area	Data Type	Range	Description
Frequency	%Q	WORD	10 - 3000 Hz	Frequency for the output signal.
Ratio	%Q	WORD	0 - 1000	Ratio for output signal.
pwfmMode	Config	ENUM	IO_PWFM_MODE_DIRECT_PWFM	Used mode (direct PWFM).
pwfmChn	Config	WORD	1-24	Configured channel.

Definitions:

error: WORD;

o_PwfmChn1_Frequency AT %QW112:WORD;

o_PwfmChn1_PulseRatio AT %QW16:WORD;

Init:

error := IO_PWFM_SET_CONFIG(i_PwfmMode:=IO_PWFM_MODE_DIRECT_PWFM, i_PwfmChn:=1);

IF error <> 0 THEN

(*error*)

;

END_IF

Run:

(* Set channel to 100Hz with pulse ratio 50%. *)

o_PwfmChn1_Frequency := 100;

o_PwfmChn1_PulseRatio := 500;

Step Motor

When step motor mode is selected, the wanted amount of pulses are defined to the output pin. The output signal frequency and pulse width can be set freely.

PWM frequencies can be configured under software control in groups of outputs.

The setting is done by a PWM channel, setting the frequency of one channel sets also the frequencies of all the other channels in the same group.
The groups are indicated with the same PWM frequency channel number in section 3720 PLCopen Addresses / 3724 PLCopen Addresses.

Name	Area	Data Type	Range	Description
Frequency	%Q	WORD	10 - 3000 Hz	Frequency for the output signal.
Ratio	%Q	WORD	0 - 1000	Ratio for output signal.
Requested Pulses	%Q	WORD	0 - 5000	Needed steps. This value is added to generated pulse count. Undone pulses can be read from this variable.
pwfmMode	Config	ENUM	IO_PWFM_STEP_MOTOR	Used mode (step motor).
pwfmChn	Config	WORD	1-24	Configured channel.

Definitions:

error: WORD;

timer1:TON;

o_PwfmChn1_Frequency AT %QW112:WORD;

o_PwfmChn1_PulseRatio AT %QW16:WORD;

o_PwfmChn1_NeededSteps AT %QW17:WORD;

Init:

error := IO_PWFM_SET_CONFIG(i_PwfmMode:=IO_PWFM_MODE_STEP_MOTOR,i_PwfmChn:=1);

IF error <> 0 THEN

(*error*)

;

END_IF

Run:

(* Set channel to 100Hz with pulse ratio 50% *)

o_PwfmChn1_Frequency := 100;

o_PwfmChn1_PulseRatio := 500;

(* Request 10 pulses every 1s*)

timer1(IN:=TRUE);

if timer1.Q then

timer1(IN:=FALSE,PT:=T#1s);

o_PwfmChn1_NeededSteps := 10; (* %Q value is set after every second. *)

else

;

end_if

Source file Topic000644.htm

Last updated 4-Sep-2025