I want to take a 0-20ma or 0-10v signal and send it into a 0-5v ADC.
I know you can turn a 0-20ma into 0-5v with a 250ohm resistor.
could you use a voltage divider to turn 0-10v to 0-5v and if so is a 250ohm voltage divider okay or should I increase the resistance?

%IW0-7 = input terminals signal
%IWcom1 = input terminals common
AI1-8 = ADC 0-5volt channels
1 switch per a channel to short a resistor of the voltage divider

would this work?

 

Yes.
250Ω will work, but it requires a 0-10V signal that can provide 20mA, and that might be asking a lot.
20mA may also lead to errors due to cable resistance.
Your microprocessor datasheet will specify a maximum drive impedance for the ADC inputs, and it will probably be about 10k, depending on the speed you want to run it at.
A 10k drive resistance would be achieved using a divider with two 20k resistors.
I wouldn't suggest using the highest possible resistance, but certainly a lot higher than 250Ω.
There is another advantage to using a higher resistance in that it will protect the ADC input better if the voltage on the 0-10V input exceeds 10V.