None of the axis are moving - using mesa 7i92t with 7i76u

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01 May 2025 21:12 #327467 by SteepLearningCurve
Hi All
Please can someone suggest next steps to try to get this to work.
I am a novice at this, so it must be something obvious, it’s just not obvious to me :)

Please see hal, ini, io attached.
I have a gantry X Y Y Z (two y motors)
I am using a Mesa 7i92TM connected from P1 to a Mesa 7i76U.
I have tried latest linuxcnc images on both Raspberry pi4 and on Intel NUC, and get the same outcome.
I used current version of mesact

The Linuxcnc dro counts on the screen, but the actual motors don’t move.
It looks like It counts in all axis until the software limits are reached, then errors.
When switched off, you can move gantry by hand in any direction.
When switched on, the gantry is rigid.
Stepper drivers are all DM556T.
Green led shows on all four of the stepper drivers (no red led on any of them)
I have wired from 7i76u to stepper drivers in differential mode, and in single ended mode with common ground, it made no difference, no axis moved.
The watchdog led in middle of Mesa 7i76U is green, and flashes approximately every second.
I have four inputs. Limit switches on the x and z axis, and proximity sensors on both ends of y axis.
In halshow, all four inputs are yellow, and go red if you trigger any of them.
Please can you suggest where to look next, or what config changes to try.
Many thanks
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01 May 2025 21:55 #327469 by PCW
I would first try setting the step time and step space to 5000 (5 usec)
since 2500 (2.5 usec) is the drives minimum (0 margin)

Also check the 5V at the 7I76U to make sure its not low

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01 May 2025 22:27 #327472 by SteepLearningCurve
Replied by SteepLearningCurve on topic None of the axis are moving - using mesa 7i92t with 7i76u
Hi PCW
Thanks for your prompt reply :)
I changed the step time and space time to 5000 for all four motors, switched off everything, and restarted , however it makes no difference (the motors don't move)
I was not sure where to measure the 5v, but choose 7i76u's TB2 connector and checked axis 0 through 3 , using the ground and +5VP on each axis, and all measure 4.9v . (The 5v comes from the 7i92T).

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01 May 2025 23:08 #327473 by tommylight
Attach a picture of the wiring here so we can have a look.

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01 May 2025 23:14 - 01 May 2025 23:17 #327474 by PCW
Also you might try checking that the direction pins change state when jogging in either direction

(you will have to disable homing to do this test)
Last edit: 01 May 2025 23:17 by PCW.

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01 May 2025 23:36 #327475 by PCW
I am using a Mesa 7i92TM connected from P1 to a Mesa 7i76U.


In that case, the configuration file is incorrect. P1 is for the second 7I76
(which has stepgens 5 .. 9)

It's expected if you have a single 7I76, that it be connected to P2

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02 May 2025 00:23 #327478 by tommylight
7i92TM should be possible to directly plug into 7i76U without cable.

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