What is the difference between Analog Output and Analog Input?

kazoo

I'm using signals to pass the data among the tasks. Currently, I'm using DO because the data passing is the boolean value. 

When I'd like to use the continuous value, I found there were two choices: AO and AI. The explanation in the manual looks pretty same. How can I use them properly? What is the difference?

BC_TN

Are you connecting the signals to a device( like a sensor, laser, etc.) or just passing data internally? If not you should be using num data or bool data to pass data between programs.

kazoo

I'm just using for passing data internally. In this case, no difference?

BC_TN

You should be using a num data and declare it as a task or make it global. You can make it a PERS to keep the data.
PERS num nWeldTime:=8.95678;

kazoo

I see what you meant. I'm connecting to another device (pc), so it's not internal. So, what is the difference between AO and AI in that case?

BC_TN

Analog Input is coming into the robot, Analog Output is going out of the robot. Normally they are for configuring and scaling an analog signal( 0 to 10v or 4 to 20 ma) to a digital number or to convert the other way around.

graemepaulin

You can digitally pass numbers by using group inputs and group outputs.

You can make the size (number of bits) to suit the data being passed (within the restrictions of the unit you are using).