I have attached a document that I am trying to understand as it relates to controlling motor speed with a ?UNO? board. The top left corner of the control diagram (page 4) appears to state that the motor can be controlled by a PWM from 10 to 50 kHZ. I am not an electronics guy but it looks like the PWM is connected to ground not 24 volts, this makes no sense to me but if the circuit is supposed to pulse the 24 volts will the board support this voltage? I am probably way off base here as I am thinking the PWM pin is just a switch to ground.
I have poked round a bit in the forums but I have not found info on this yet.
Thanks for any info
The circuit shows a PWM voltage source in the customer circuit shaded box. Voltage
sources don't need a supply, they just magically generate a voltage!
That diagram is woefully inadequate, doesn't tell you what voltage is needed for
the PWM! Perhaps it works at 5V, perhaps at 10V ? The same line can be used for
analog input in the range 0..10V, which makes me suspect the controller just has
an RC circuit in it, so that the PWM would need to be 10V to get full speed
(5V PWM would only give half the range).
It is inadequate ...by a large margin.
Im looking it over .It appears that this might be a chopper circuit.
These types of fan's are really common on heaters/defrosters in alot of European equipment,(Dozers,Cranes,trucks)..
Its not so much the pulse width as it is what type of pulse at what voltage.Its likly simple though.
Hi, if you want to find out how PWM controls a motor, that document is not going to do it.
It is showing how to control the motors built in controller.
Try googling, arduino dc motor pwm control
Tom.. 
The controller appears to expect a 10V or greater PWM signal, since the other control mechanisms show a 0-10V DC input or a pot driven from a 12V supply. There is evidently a smoothing capacitor inside the unit, behind the 75K resistor. You will need to use some external hardware (e.g. NPN transistor + 2 or 3 resistors + 12V zener diode) to drive that control input from an Arduino PWM pin. You will also need to increase the PWM frequency from the default 490Hz.
Well I have purchased a Arduino ultimate starter kit, it has a book, a temperature sensor that should serve and transistors that should let me switch the 10 volts that I will achieve off the 24 volt supply using a voltage divider to control the motor via the PWM function. We have a plan. Thanks for the help though none of it was specific answers it gave me enough information to attempt to let the smoke out of some components.
MarkT:
The circuit shows a PWM voltage source in the customer circuit shaded box. Voltage
sources don't need a supply, they just magically generate a voltage!That diagram is woefully inadequate, doesn't tell you what voltage is needed for
the PWM! Perhaps it works at 5V, perhaps at 10V ? The same line can be used for
analog input in the range 0..10V, which makes me suspect the controller just has
an RC circuit in it, so that the PWM would need to be 10V to get full speed
(5V PWM would only give half the range).
Finally found the reason!
Your guess is right, when I use esp8266's 5v (not 3.3v) PWM, it gives me half speed. How to use esp8266/ESP-12F/or Arduino to control ebmpapst 48V DC fan? - Motors, Mechanics, Power and CNC - Arduino Forum
But how to get 10V PWM to control it then? Or 10V variable voltage if thatls eaiser?
level shift a logic signal to 10V using a MOSFET low-side driver perhaps?