AC servo with 7i93 board
I find these in aliexpress but I think they do the pid internally in the driver... or it is possible to do the pid in linuxcnc. connecting the encoder directly to the 7i93.
servo motor link:
ac servomotor link
ac servo motor 2
This type of drive would typically be run open-loop (no encoder feedback) from LinuxCNC
You can drive its opto-isolated step/dir inputs directly from the 7I93 but you have to be very careful that you do not exceed the I/O voltage/current limitations by:
1. Shorting 7I93 I/O pins to frame grounds (that may have as much as a couple volts difference from 7I93 power ground at high frequencies .
2. Shorting 7I93 pins to any external voltage exceeding their -0.5 to+7V range
To drive opto-coupler pins directly from the 7I93, you connect the + input to 5V
and the - input to the 7I93 output. This guarantees a full 5V drive signal.
They have an encoder output to take into linuxcnc for closing the loop. I have had this working on a 5i25/7i77 setup.
They come with the loop closed in the drive. You have to change the parameters in the drive to make this work. IT does work though as I have had it working on a friends machine. It also does velocity mode +-10v.
Good luck, once setup they are solid.
I think I'll buy the kit 5i25 + 7i77
apparently it seems easier to setup!
I'm looking at the Delta's servo motors to buy.
AC Motor: ECMA-C20807ES
My question is, in speed mode, where the encoder would be connected
AC motor encoder >> 7i77
AC motor encoder >> Drive >> 7i77
since the drive emulates the encoder output.
Tavares wrote: I find these in aliexpress but I think they do the pid internally in the driver... or it is possible to do the pid in linuxcnc. connecting the encoder directly to the 7i93.
I am successfully using those AASD controllers and 80ST-M02430 / 110ST-M06030 motors, but through the parallel port and some "simple" level-shifting circuits, not the 7i93.
I can tell you that these motors are readily configurable for step/dir or quadrature position, analog speed, or analog torque control, so they should work directly with any of LinuxCNC's possible open/closed PID configurations, which includes torque mode with LinuxCNC closing the loop on feedback from the motor's position encoder. But the signals are 12VDC level to the AASD, except the encoder output which is 5V differential. The documentation is full of puzzles and mysteries about how these features work, but they do work.
PCW wrote: At least the first link shows that the drive has a step/dir interface and no position feedback to the controller (LinuxCNC in this case)
The AASD servo drive does indeed provide the motor's quadrature position feedback as 5V differential signals on the DB-25 connector. This is at native 8000 steps/rev, and you can set software gearing to any smaller steps/rev you like. This is a near-perfect feature, once you figure out the Engrish documentation describing it as "molecules" (numerators in ratios).
I'm thinking about the diameter of the ball screw. In the project I used ball screw of 16mm, I do not know if I need 20mm because it is a big machine 3000x2000.
Mesa board: 7I77-5I25
Driver Ac Servo Driver: ASD-B2-0721-B (manufacturer Delta)
AC Motor: ECMA-C20807ES 750W Torque 2.39Nm, 3000 RPM - Encoder 17 Bits - Shaft 19mm (manufacturer Delta)
ball screw : 1605 (16mm )
Iam thinking in change the ball screw to 2005 or 2010, what u guys think? I want fast and Strong
and without spending a lot of money.
Take a look at my projet
My CNC 3d-Sketchup File