Author Topic: Connecting Lichuan AC Servo to PMDX-126  (Read 179 times)

Harley95

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Connecting Lichuan AC Servo to PMDX-126
« on: December 06, 2019, 10:13:09 PM »
I have a Lichuan AC servo that I am hooking to be used as my spindle motor. And would like input as to if I am connecting it up correctly?

After speaking with Lichuan engineers they have sent me a diagram with what needs to be connected in order to get the drive functioning but I am not sure of the electrical diagram for the step and direction. I am not sure of what the wave symbol in the lower part of diagram between the controller and pulse and direction means?  The PMDX-126 only has 1 output for each step and direction but the diagram shows a negative and positive for each of the step and direction. My interpretation of the diagram is that I apply 5v to the positive of both the step and direction and hook the negatives to the step and direction outputs of the PMDX-126. It also states that if using 5v no resistor is needed.

As for the servo enable SON (per diagram)  I plan to connect that to the J13 RST and the Input common ground to J13 COM.
As for the Servo ready signal I am not sure where this should be connected.

Thanks
Jeff


12strings

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Re: Connecting Lichuan AC Servo to PMDX-126
« Reply #1 on: December 06, 2019, 11:33:41 PM »
The "wave" symbol means "twisted pair", where the signal wire and its associated +5V or GND wire are twisted together.  This help reduce the effects of electrical interference/noise.

The wiring scheme they show (using +5V and step/dir) requires the step and direction signals to be 'active low".  This is possible in Mach3/4.  You can also wire them as "active high" signals by runing the step/dir signals to the "+" terminals and GND to the "-" terminals.  With the PMDX-126, you can get either the +5V or GND from the PMDX-126's J1 to J4 connectors (PC+5V or PCgnd).  See also the PMDX FAQ:

https://faq.pmdx.com/content/5/11/en/how-should-i-connect-pul-pul_-dir-and-dir_-on-my-motor-drivers.html

Regarding the "enable SON" - what does that input do?  The PMDX-126 "RST" output is 2 second long pulse whenever outputs are enabled (see the PMDX-126 User Manual section 7.3).  If the "SON" input needs a constant connection to COM to enable the servo driver, "RST" won't work.  The real question is why do you want to connect the SON input to the 126?  Do you really want/need the PC to be able to enable and disable the servo driver?

Harley95

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Re: Connecting Lichuan AC Servo to PMDX-126
« Reply #2 on: December 07, 2019, 08:29:55 AM »
Thank you for the help 12string,
I believe enable SON is what tells the drive it's ok to accept commands. The servo ready I am assuming would be an input on the PMDX-126.
The manual does not give any explanation of definition of each connection.


12strings

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Re: Connecting Lichuan AC Servo to PMDX-126
« Reply #3 on: December 17, 2019, 11:57:56 PM »
Sorry - been away from the computer for a while.  For starters, I would simply wire the SON to whatever its "let the drive run" state (either open or shorted to COM), and leave the servo ready signal unconnected.  Once you get the system working, you can see if the servo ready can be tied into the PMDX-126's ERR input.  And/or look at having the PMDX-126's "charge pump OK" signal drive the SON input to enable the servos.