Hardware for linuxcnc to control servos

Hello!
Iam new to linuxcnc but not to linux.
I want to control in closed loop to linuxcnc 2 dir/step AC servos with 4 inputs / 4 outputs (each one) / ABZ optical rotary encoder 2500ppr as feedback.
Also because these servos are for a lathe i want to get feedback from spindle for threading purposes and control the spindle speed with a vfd to have constant surface speed (0-10v analog control voltage).
What hardware i need to control these servos at full speed (500khz pulses) get feedback from spindle and control the vfd speed ?
Can you suggest me hardware that fits in my needs ?

Because i have already 3 parallel ports can i set temporarily the servos (not at full speed) with parallel ports ?
Iam searching a good linuxcnc tutorial for set up servos with parallel port..

Thank you

vre wrote:

Hello!
Iam new to linuxcnc but not to linux.
I want to control in closed loop to linuxcnc 2 dir/step AC servos with 4 inputs / 4 outputs (each one) / ABZ optical rotary encoder 2500ppr as feedback.
Also because these servos are for a lathe i want to get feedback from spindle for threading purposes and control the spindle speed with a vfd to have constant surface speed (0-10v analog control voltage).
What hardware i need to control these servos at full speed (500khz pulses) get feedback from spindle and control the vfd speed ?
Can you suggest me hardware that fits in my needs ?

Because i have already 3 parallel ports can i set temporarily the servos (not at full speed) with parallel ports ?
Iam searching a good linuxcnc tutorial for set up servos with parallel port..

Thank you

If you really want to use step/dir servo drives, there is the Pico Systems Universal Stepper Controller, as well as some
products from Mesa. See <pico-systems.com/osc2.5/catalog/product_...ath=4&products_id=30>
for info on that. Pico Systems also has a PWM servo control system, consisting of the PWM controller
and the brushless PWM servo amps. See <pico-systems.com/osc2.5/catalog/index.php?cPath=3>
for those products. This gets away from the concept of steps entirely, and just handles encoder
position and velocity to the servo drives.

Jon

thank you for your reply.
I want to close loop in linuxcnc (outer closed loop) not in servo drive (inner closed loop) but parallel port isn't fast enough
for 500khz which are my servo drives so i want a fast hardware to send 500khz dir/step pulse in my servo drives
and read 500khz encoder ABZ servo driver signals for closing loop in linuxcnc.
Because iam confused which card its in my situation ?
This project works ? code.google.com/p/rt-8p8c/
Also because iam totally new exists any good tutorial for servos and linuxcnc (parallel port)?

vre wrote:

thank you for your reply.
I want to close loop in linuxcnc (outer closed loop) not in servo drive (inner closed loop) but parallel port isn't fast enough
for 500khz which are my servo drives so i want a fast hardware to send 500khz dir/step pulse in my servo drives
and read 500khz encoder ABZ servo driver signals for closing loop in linuxcnc.
Because iam confused which card its in my situation ?
This project works ? code.google.com/p/rt-8p8c/
Also because iam totally new exists any good tutorial for servos and linuxcnc (parallel port)?

Sorry, I know nothing about that board, I've never heard of it before.

I know my Universal Stepper controller does work in a mode where the
encoders feed back position info to the board, and the loop is closed
in LinuxCNC. This allows you to tune the servo response with
Halscope and the Calibration menu. We also have the Gecko Interface,
which makes an opto-isolated copy of the encoder signals for the
servo drive. it was designed to be used with Gecko 320 step-servo
drives, but likely could be used with others, too.

Jon

How can i config linuxcnc to work servos from parallel port ?
Where can i find an example configuration ?
Also can i use ethercat with linuxcnc in my servos (my servos accept step/dir signals 500khz) ?

thank you.

vre wrote:

How can i config linuxcnc to work servos from parallel port ?
Where can i find an example configuration ?
Also can i use ethercat with linuxcnc in my servos (my servos accept step/dir signals 500khz) ?

thank you.

If you need 500 KHz step rates, you MUST use hardware assist. If you want to use the
parallel port, you can use the Pico Systems Universal Stepper Controller. While it is
conservatively rated at 300K steps/second, it can actually do 500K, that will just make the
jitter slightly worse in percentage terms. The step clock is 10 MHz, or 100 ns, so that at
500 K steps/second, the resolution is 100 ns out of 2000 ns, or 5%. Since it is a
servo, there would be no possibility of lost steps.

Software step generation through the parallel port will not be able to go much over 50 KHz.

Check out the USC board at
pico-systems.com/osc2.5/catalog/product_...ath=3&products_id=19

it is attached to the computer through the parallel port, which is used as a communications
channel to send position back to the PC and step rate to the UPC.

The univstep config directory in the LinuxCNC sample configs is specific to this
board.

Jon

Other option than pico system exists ?
For example a solution with ethernet port or something from mesa electronics ?