Click PLC PWM Output

[juddge]

Hi guys, i have never had to do a PWM Output or input before

i have a Device that to dimm the lamp output from the ballast, the ballast has a 24V PWM input
i need my PLC to output this to the ballast
but i dont want it a dial like the manufacture advised

i want to create 3 settings for power output of lamp
so lamp will run at 3 power settings 50%, 75% and 100% now i have noticed by default if i just apply 24V dc directly to this contact its allow full power
so is the PWM just dropping the voltage ?
and the settings of the PWM in the click sofware confuse me
it wasnts cuty cycle ? is this where i specify the 50,75 and 100 ?
sorry to be a pain but i really want to get my head around this

 

[FearTheNoFear]

so is the PWM just dropping the voltage ?

Yes and no. Remember a PWM signal is a square wave between (in your case) 0V and +24V. 100% is full 24V all the time. 50% is half the cycle at 0 and half the cycle at 24V. 20% is 4/5 of the cycle at 0V and 1/5 of the cycle at 24V.

it wasnts cuty cycle ? is this where i specify the 50,75 and 100 ?

Correct, duty cycle is where you put those numbers. I'm not familiar with the AD PLCs but would like to tinker with them someday.

 

[juddge]

it appears so

manufacturer specifies input as
Type - 1-5KHZ , % PWM

thats where im confused it wants both a KHZ and duty cycle ?
does it mean any signal between 1-5khz with the duty cycle to determing % ?

so set at 1KHZ signakl with 50% duty cycle will create 50% dimming ?

 

[FearTheNoFear]

does it mean any signal between 1-5khz with the duty cycle to determing % ?

PWM has two components to it: frequency and duty cycle. Frequency is how many times a second it pulses. Where duty cycle states how big of a pulse it is in one cycle.

so set at 1KHZ signakl with 50% duty cycle will create 50% dimming ?

Yes that is correct. Anything lower than 1kHz or higher than 5kHz and it won't recognize it as a signal. Setting it at 2kHz at 50% would still yield a 50% dimming. I would go at 2.5kHz as that's right in the middle.

 

[juddge]

PWM has two components to it: frequency and duty cycle. Frequency is how many times a second it pulses. Where duty cycle states how big of a pulse it is in one cycle.



Yes that is correct. Anything lower than 1kHz or higher than 5kHz and it won't recognize it as a signal. Setting it at 2kHz at 50% would still yield a 50% dimming. I would go at 2.5kHz as that's right in the middle.

Ok thank you , now it makes sense- thank you for your explanation

I greatly appreciate your assistance - I will sample to code tonight and when working - reply with the results

 

[OkiePC]

I haven't used the Click Plus high speed outputs but I have used their high speed inputs. The setup dialog box appears to make it quite easy. The Help file adds some details too. You simply pick the desired addresses for frequency (Long integer, DD register 0 to 100,000 Hz) and Duty Cycle (Also a DD register, long integer with one implied decimal place, so 0 to 1000 is 0 to 100.0%).

After you set that up and download, just put the PLC in run mode and pop values into those two DD registers to control the output.

Your ladder logic would need to write values to those two DD registers to control the output.

 

[juddge]

So , code was input , it appears to be running
Cannot try until I get the an old UV lamp to try with the ballast
But will also need to run a temp 25A circuit for the ballast

I will experiment when I have time this week and let everyone know
But it appears all your answers have guided me to the right decision
Thank you everyone