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Dear All,
I have an old milling machine with a hydraulic spindle speed range switch. The hydraulic valve has 2 coils (low and high speed). There are 2 feedback inductive sensors (for low and high speed).
How can I solve this so that when a program needs to change the speed range, it does so automatically under the following conditions.
- the spindle can only rotate (in the between min-max range (50-3200rpm) if the inductive feedback corresponding to the speed
- the range can be changed by reducing the speed to 1-2 rpm
- low range (50-1500rpm)
- high range (1501-3200rpm)

I am looking for advice on how I can solve this properly. (I have never done this with Linuxcnc before)

Jdolecki wrote:

How  does the servo driver know I want to switch from turning to position for milling?
 

As @Aciera pointed out, there are (at least) two methods for combining a velocity-mode spindle with a position-mode C-axis.

In Aciera's first example (caxis.comp) the servo driver doesn't 'know' anything about turning vs positioning.  The drive is put in position mode, and LCNC (via caxis.comp and PID tuning) handles positioning vs velocity commands.

In the second example, the drive itself is switched between velocity and position modes using an input on the drive.  LCNC handles the mode switch command, as well as appropriate outputs to the drive depending on which mode is desired.

Neither one of the methods is 'official' Linuxcnc.  That means you won't find official simulations & examples, nor will you find caxis.comp in the official repository.

If you only need to index the C-axis, it will be significantly easier to use orient.comp to position the spindle.  Simplified, orient.comp works by creating two PID loops (one for velocity, one for position), and switching between the two using an M-code.  With orient.comp, there is no 'C' axis available to command - just the spindle through M3/M4/M5 and M19 to position it.

When stopped, the spindle can be positioned at any location using an M19 command - just fine for drilling or X/Y axis milling.  And with a servo-driven spindle the position should be pretty stable.  Heavy milling or drilling which imposes a significant rotational force on the spindle would likely require a brake of some sort.

However, if you need continuous spindle movement coordinated with one or more other axes (X/Y/Z) during milling you will have to use one of the above 'unofficial' methods (or create a new scheme).

@Aciera - 

I had hoped to duplicate your C-axis process back when you were working on it, but my drive doesn't permit on-the-fly mode switching via external input.

Since I don't think I can use orient.comp and caxis.comp on the same joint, I'm thinking about ways to un-home and re-home the joint/axis.  Caxis.comp doesn't re-home or move to C0 whenever the spindle stops - it returns to the same position it was in when the spindle command was issued.

Since I don't need to freewheel in the middle of a program, what do you think about using halui to unhome/rehome the C-axis?

• Freewheel button ON (M-code)
  • set halui.joint.C.unhome
  • Latch encoder reset pin HIGH (to keep it at 0)
  • Amp enable OFF
• (manual spindle rotation activity)
• Freewheel button OFF
  • Amp enable ON
  • Unlatch encoder reset pin
  • set halui.joint.C.home

See any major issues with the above before I try testing it this evening?

Please help me with the wiring of a single CL57T-V4.1 closed loop driver to Mesa 7i96S

( I am able to get PnCconf to see the Mesa 7i96S board. )

This is the manual of the CL57T driver: www.omc-stepperonline.com/download/CL57T_V4.0.pdf

The printed manual comes with the driver is version CL57T-V4.1, but I can't see any difference.

Based on the manuals for the driver and 7i96S, I understand that:

● Mesa 7i96S STEP pin is the Driver PUL pin. E.g., for a 1.8° step motor, 200 PULSES is a full STEP.

● Mesa 7i96S DIR pin is the Driver DIR pin. I.e., Clockwise or Counter Clockwise.

● The CL57T_V4.x driver requires input voltage 18-50VDC (recommended 24-48VDC). Peak Current: Minimum 2.4 (RMS 2A), typical 5.6 (RMS 4A), max 7.0 (RMS 5A). So it is not a "higher than normal input current requirements" as per Mesa 7i96S manual page 12.

● The CL57T_V4.x driver supports both differential inputs and single-ended inputs. ( I'll wire it to use differential inputs, since it offers better performance. )

And so I am going to attempt this:



1. Is the wiring correct please?

2. The driver manual, page 7, states:

[
The 1-bit selector is located on the top (S3 in figure 2), used to configure the voltage of control signals. For the safety of optically coupled, the factory setting is 24V, which no need to connect 2K resistors, making it easier to use. When the voltage of the control signal is 5V, the S3 must be set to 5V, otherwise, the motor won't work.
]

To use the driver using Rasberry Pi 4 as a controller, I have to set the driver S3 to 5V ( I have documented in this video: )

Using it with 7i96S, should I set it to 5V or 24V, please?

3. Do we just leave the driver ENA, ALM and BRK un-used, please?

Thank you.

Yeah I posted that patch in my first post.
You taught me the way royka