Retrofit 7 ton HOMAG with Rexroth motors and drives - mesa 7i97t

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13 Feb 2026 15:53 - 13 Feb 2026 15:55 #342893 by Nkbhvid
Hi there
I am retrofitting a giant 7 meter and 7 ton Homag BMF 411.
When it left the factory in 2005 it was equipped with Indramat servos (today Rexroth) and Rexroth DKC 03.3 drives with sercos I communication. 
With a great deal of willingness from our local Rexroth technicians i managed to reconfigure the drives to analog com and now the drives are updated with new firmware ready to be re-installed in the machine.
I have managed so far to connect the 0 joint -x axis-  to my mesa 7i97t ethernet card and i can see the DRO increasing/decreasing respectively when I rotate the motor by hand. So all in all a first table setup with one motor no limit switches, motor brake and enable signals are still not coming from linux but directly from UPS.
Here are my problems:
1  When I enable the drive the mesa card throws out 1 volt to the analog pin and the motor starts turning at a speed that looks OK like 10% of speed max.
2. When I jog the motor in continuous mode the x axis DRO counts up 0,18 mm when pressing and another 0,18 when releasing the tab - same result if i use the jog arrows in axis.
Any ideas?
I am not a linux specialist - in fact this is my first time putting fingers to a linux pc but i have been working with CNCs for 3 decades 
 

File Attachment:

File Name: homagretrofit.txt.ini
File Size:2 KB
 

File Attachment:

File Name: main.txt_2...2-13.hal
File Size:3 KB
Attachments:
Last edit: 13 Feb 2026 15:55 by Nkbhvid.

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13 Feb 2026 17:55 #342896 by PCW
If you set all PID values to 0 and you still get 1V outputs  from the 7I97T analog outputs
,the 7I97T is likely damaged

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13 Feb 2026 18:13 #342898 by Nkbhvid
I wonder how this could be damaged?
it has never been connected to anything else but 5 volt, Ethernet, one encoder and one analog out? It has never been installed and has never left the table.

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13 Feb 2026 18:38 #342900 by PCW
Missing grounds between a large machine and the controller can easily damage
analog and encoder pins, that is, unless a permanent ground exists between
the machine and the control electronics. there can easily be enough potential
difference to damage electronic connections.

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13 Feb 2026 18:56 - 13 Feb 2026 18:58 #342902 by Nkbhvid
Hmmmm
as said: it has never left the office desk and has never been near a “large machine” in real life.
If damaged it can only be because of the failed attempts to connect to LinuxCNC.
Last edit: 13 Feb 2026 18:58 by Nkbhvid.

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13 Feb 2026 19:31 - 13 Feb 2026 19:34 #342905 by PCW
Failed communication connections are a software issue.


If you power the 7I97T (and not run LinuxCNC), do you read
near 0V on all analog outputs? (that is, less than 15 mV)
Last edit: 13 Feb 2026 19:34 by PCW.

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13 Feb 2026 19:49 #342906 by Nkbhvid
The 6 axis ranges from 9-11mv

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13 Feb 2026 19:58 #342907 by tommylight

The 6 axis ranges from 9-11mv

The 6'th axis or all 6 axis?

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13 Feb 2026 20:11 #342911 by Nkbhvid
Axis0 11mv
Axis1 9mv
Axis2 10mv
Axis3 9mv
Axis4 10mv
Axis5 9mv

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13 Feb 2026 20:45 #342913 by PCW
OK that looks good.

The next test is to set all PID pins to 0 (P,I,D,FF0,FF1,FF2) in the ini file
and start LinuxCNC, then enable motion, at this point, PWM should be enabled on all axis
but the PWM value should be 0 on all axis. Again measure all the Analog outputs.

Also insure the all PWM enables are true, and all PWM values are 0

 (test done with nothing connected to the 7I97T except 5V power and Ethernet)
 

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