t100md 888 pwm

[kenobe]

Hi
I try to use the pwm channel 1 (pin 7) to control the speed of my 24 volt dc motor.
I use function setpwm 1,8000,32000.
but when I measure the ouput of pin 7. I dont get the pwm waveform and my dc motor is running at full speed.
What should I do to control the speed of the 24v motor

[support]

Usually DC motor being an inductive device would not let the PWM current change rapidly enough to sustain a 32KHz PWM. You can try a lower frequency such as 2KHz and you should be able to get a nice wave form.

[kenobe]

Hi
Thanks for your fast reply.
I did tried 2kHz, but result is the same ie: no pwm output wave form and motor running at full speed.

Do I have to do some more things to initialise the pwm beside setpwm 1, 8500,20000?

Thank you very mush

[support]

That's the only command you need to use. Are you able to turn the PWM to fully ON by setting duty cycle to 100% (10000) and fully OFF by setting duty cycle to 0% ? If not then your output driver may be bad.  

[kenobe]

Hi
Thanks for your advise
It is conformed that the driver was bad.
How do I replace the driver chip, which IC? where can I get the replacement?

Thanks

[support]

Did you check both channels of PWM outputs? Is one channel working and another not working or both not working as you expected. If both are not working as you expected it maybe a wiring issue.  The best is not to connect the PWM outputs to any load and then use the SETPWM command to turn the output to fully ON, 50% duty cycle and and fully OFF and observe if the LED is turned ON and OFF accordingly.

The PWM output driver on T100MD888+ is IRL530N. It is a TO220, three pin device (looks like a power transistor) and need to be desoldered. If you are not comfortable handling a soldering iron then it is best to contact your distributor or if you have purchased from us directly then email to support@tri-plc.com and request for an RMA # and send the PLC back to us for repair.

[kenobe]

Hi
Thank you for your reply
I figure out that both pin 7 and 8 have no output.
I will replace the IRL530N.
Thanks again for your support.