Using closed loop with Maxxon drivers

Hey guys,

I'm trying to use Maxxon drivers in closed loop with CNCLinux, but I am having trouble in the configuration. Does the CNCLinux have the option to work in closed loop throught the parallel port (using encoders) with a non-Mesa driver ?

Thanks !

sure
Here's an example:

emergent.unpythonic.net/projects/01142347802

leonardo.calixto06 wrote:

Hey guys,

I'm trying to use Maxxon drivers in closed loop with CNCLinux, but I am having trouble in the configuration. Does the CNCLinux have the option to work in closed loop throught the parallel port (using encoders) with a non-Mesa driver ?

Thanks !

If you are sending step/dir signals out the parallel port, there are very few pins left to
read encoder position. You would have to add at least one additional parallel port
set for input to get the encoder signals into the CPU. But, the speed at which the
software encoder component can read encoder counts may be too low.
You can calculate the rate. Motor RPM / 60 * encoder line count * 4 (for quadrature)
will be the quadrature counts/second rate. You need to have somewhat more than
this number of base thread dispatches/second, or encoder counts will be missed.
In the .ini file, there will be a line that reads BASE_PERIOD = xxxxxx
this is the dispatch period in ns, so that number / 1000000000 = time in seconds,
then 1/x that is BASE rate in seconds. So, a BASE_PERIOD of 20000 would be
20 us or 50,000 per second, which might reliably read an encoder count rate
of 30,000/second.
Unless your encoder resolution is low, or your speed is kept low, you may
exceed the ability of the software encoder component to keep up. Exceeding
this will cause a servo runaway, which is not a good thing.

So, a better way is to use external hardware to do this. The Pico Systems
Universal Stepper Controller can do this, and there are Mesa and other
products as well.

Jon