Problem when analog input channel was set as primary feedback.

[Ya-hoo]

I need to switch primary feedback from encoder 1 to ADC 1 programmatically in my program to control velocity and pressure respectively.

A DC signal from function generator was used to simulate pressure feedback analog signal in my test.

I had a small program is attached.
Some problems have been encountered in this small test.
1. The motor didn't stop at setting position because move complete is polling out at second while loop and that move complete turn to True once the motor start to run.

2. When the analog signal's value was changed, the motor start to run, but neither the program nor MAX was running at that time.

Questions:
1. How can I set move complete criteria? None of them is chec
ked in move complete criteria setup page for my test.

2. When analog input is set as primary feedback, the position input should be the desired pressure. What the velocity input should be at this point?

3. I didn't do tunning for pressure control because the whole system hasn't been hooked up. Could that be one of the reasons that the motor got running when analog signal changed? Because when I didn't velocity control system tunning for other equipment, similar thing happened. As long as controller and driver were powerd on, the motor got running and I found it was caused by inappropriate control gain.

Any opinion is very welcomed.

Thanks.

[ColinAE]

Hello.

1. How can I set move complete criteria? None of them is checked in move complete criteria setup page for my test.
In the Axis Settings-Trajectory Settings Move Complete Criteria, you can set a variety of conditions for move complete. You might consider checking some of those criteria and check the effect it has on your system.

2. When analog input is set as primary feedback, the position input should be the desired pressure. What the velocity input should be at this point?
The velocity level can be whatever you wish, it is simply going to be a function of how fast the controller tries to move the motor to the desired pressure. I believe your question is 'What exactly is velocity in this context?' If that is your question, it is the numbe
r of ADC bits (counts) per second.

3. I didn't do tunning for pressure control because the whole system hasn't been hooked up. Could that be one of the reasons that the motor got running when analog signal changed? Because when I didn't velocity control system tunning for other equipment, similar thing happened. As long as controller and driver were powerd on, the motor got running and I found it was caused by inappropriate control gain.

Indeed, you will need to do the tuning with the different feedback connected, as it will dramatically affect the way the controller behaves. If you are switching between different primary feedback sources, you should programatically load new PID gains for each type.

Hope this helps.
Regards,
Colin C.
Applications Engineering