concerns about pmdx-424

[isound]

Hello.

This is my machine with 3axis 5 motors. I  added A axis so 4 axis 6motors.

I managed to drive 4axis 6 motors with TINYG(2 z axis + 1X 1A axis 1Y axis + 1Yaxis{external driver} ),  but  need more stable operation because chilipeppr crashes over 5MB Gcode everytime.

1. Y & Z axis -> 2 drivers for each axis -> 4 motors will work. 424 has motor3a motor3b but I should connect 2 drivers(z axis) to motor 2.

What's different between having 2 motor3 and connecting 2 driver to motor2?


2. This inverter has manual speed control knob, I don't know how to enable pmdx-407 speed control.

If you want to gimme advice, it will be appreciated.

[Steve Stallings]

On the PMDX-424 the Motor 3 output is special because it commands
the two motors to rotate in opposite directions as is needed for two
motors facing opposite directions when mounted to drive opposite
sides of a moving gantry.

It is possible to connect two motor drivers to any of the other Motor
outputs on the PMDX-424 but the two motors will be commanded to
run in the same direction. These outputs can supply 24 milliAmperes
which can safely drive the opto-coupler inputs of two drivers wired
in parallel.

If you can provide a link to the manual for your inverter, we can give
you instructions for setting it up to work with the PMDX-407. The
picture shows the type of VFD (inverter) that the PMDX-407 was
designed to control, but we will need the manual to identify the
functions of the control terminals, and to determine how to set
the parameters to switch from panel control to remote control.

Steve Stallings
www.PMDX.com

[Bob at PMDX]

It is possible to connect two motor drivers to any of the other Motor
outputs on the PMDX-424 but the two motors will be commanded to
run in the same direction. These outputs can supply 24 milliAmperes
which can safely drive the opto-coupler inputs of two drivers wired
in parallel.

To expand on this a bit - connecting the step/dir signals from 2 drivers to the same step/dir outputs on the PMDX-424 (or any SmartBOB) will indeed tell the drivers to move both motors in the same direction.  However, you can change the motor wiring to one of the motors to make it turn the opposite direction *if* you need that.  Simply swap the two wires from ONE phase of the motor (i.e. swap the A and A-BAR wires).

The other difference between using the 3A and 3B terminals to drive two motors and wiring 2 motors to a single step/dir output is that the 3A and 3B outputs will (eventually) be able to square the gantry during homing (i.e. run the 3A and 3B motors independently).  This is not yet supported in the firmware but is coming.

Bob

[isound]

Thank you two guys. I got what's the different.

A chinese VFD (maybe the best seller) 's manual is here.

http://www.jinlantrade.com/ebay/invertermanual.pdf

this manual has a lot of text.

https://www.youtube.com/watch?v=tGGU0smK2Wc

This movie shows probably the same model with speed control knob.
2 wires connects RS+ RS- and speed controller. And remote control works.

407 could be wired like it?

[Steve Stallings]

That video shows using MODBUS serial to control the VFD. This uses a serial
port and requires software that can talk to the VFD.

The PMDX-407 uses an analog control voltage and simulated switch contacts
to control the VFD, so it interfaces in a very different manner.

The connections required are:

PMDX-407        VFD
------------------------------
Aref                  10V

Aout                 VI

Agnd                ACM

RUN                  FOR

COM                 DCM

You must also set two parameters in the VFD to instruct it to listen
to the control terminals instead of the front panel. They are:

PD001 must be set to a value of 1
this selects External Terminals as the source of the run command

PD002 must be set to a value of 1
this selects External Terminals as the source of the operating frequency

Instructions for programming parameters in this VFD are not very
clear in the manual. I recommend looking at this YouTube video:

https://www.youtube.com/watch?v=a-8NR5XY8CQ

The programming example starts at about 5:10 into the video.