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step_type, control-type

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24 Jan 2025 18:50 - 24 Jan 2025 18:51 #319774 by slowpoke
step_type, control-type was created by slowpoke
I'm in the process of getting EMC2 AXIS working for a lathe.
  • I'm using an open loop step and direction type stepper for the Z axis
  • I'm using a step and direction type servo with integrated encoder for the X axis
  • I'm using a 7i96s to drive the stepper and servo
  • I have linear scales, however I'm not using them to close the loop because the factory lead screws have lots of backlash, so open loop for now.

    Both axis are moving as commanded, however probably not optimized.

    1) When I look in my CX706-R0.hal file I see some setp lines (for example line 115-124) that I suspect are not applicable and should probably be deleted for clarity but I'm not sure, because I'm not using a closed loop stepper for joint 1 (Z-axis) or perhaps these lines are needed but just the title "# ---closedloop stepper signals---" is confusing. Are these line needed?

    2) Line 61  setp   hm2_7i96s.0.stepgen.01.step_type        0
        My understanding is 0 = quadrature type , and I think this might supposed to be set to 1 for step and direction?

    3) Line 62  setp   hm2_7i96s.0.stepgen.01.control-type     1
        I"m not sure if this is correct,  first should this be position or velocity and is position 0 or 1?

    If you spot anything else that looks questionable in the HAL file please comment, I'm slowly getting up to speed but still have a lot of blanks in my understanding of how this all comes together.

    Thanks in advance to any responders.
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Last edit: 24 Jan 2025 18:51 by slowpoke.

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24 Jan 2025 18:56 #319776 by PCW
Replied by PCW on topic step_type, control-type
pncconf sets up Mesa hardware stepgens correctly, no changes are needed unless
you want a non-standard step type. (pncconf defaults to step_type 0 = step/dir)

From the hostmot2 manual page:

      step_type (u32 r/w)
           Output format, like the step_type modparam to the software
           stepgen(9) component: 0 = Step/Dir, 1 = Up/Down, 2 = Quadrature, 3+
           = table-lookup mode.
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25 Jan 2025 00:27 #319795 by tommylight
Replied by tommylight on topic step_type, control-type
Position mode = 0
Velocity mode = 1
Step type 0 = step/dir
Step type 1 = up/down
Step type 2 = quadrature
I think, been 15 years since i was deep into it, there are 10 step types, so 3 should be 3 phase at 120 degrees, and some more 4 pin types, and 5 pin/phase types.
Yes, LinuxCNC can do 3 and 5 phase stepper control, i still have some of those in the shop, i was very happy when i saw 5 phase motors move using 5 darlington transistors and 5 resistors from a parallel port. :)
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  1. Configuring LinuxCNC
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