Test LinuxCNC without motors and encoders connected

More
06 Jun 2019 18:48 #136078 by Peterdeleu
Hi @ all

I've received my Mesa cards (5i25, 7i77 and 7i84) today.
At first, I was unable to start LinuxCNC after a PnCConf.
It looks like the firmware on the 5i25 wasn't correct.
After loading the firmware "5i25_7i77x2.bit" the problem was solved.
Now LinuxCNC starts without a problem.
The spindle motor is configured on DRV5 and I can read a value from 0-10v on that port if I turn the spindle on.
However, I'm not able to home the machine. I get a "Joint 2 following error".
I think this is because I don't have a motor/encoder connected.
The LinuxCNC tries to move the servo, but the encoder doesn't provide signals. Is this correct?

Questions:
Will the 7i84 work with this firmware? (not yet connected)
Is there a way to overrule the presents of a servo/encoder, so that I can check If I get a 0-10v output on DRV1, 2 and 2.

Regards
Peter

Please Log in or Create an account to join the conversation.

More
06 Jun 2019 19:33 #136080 by PCW
The LinuxCNC tries to move the servo, but the encoder doesn't provide signals. Is this correct?

Yes, you will get a following error because the feedback position does not match the commanded position

Will the 7i84 work with this firmware? (not yet connected)

The 7I84 (and all SSerial cards) don't depend on card specific firmware,
they will work with any daughtercard that has a SSerial interface

Is there a way to overrule the presents of a servo/encoder, so that I can check If I get a 0-10v output on DRV1, 2 and 2.

You can set the following error limits quite wide

Please Log in or Create an account to join the conversation.

More
06 Jun 2019 19:47 #136083 by Peterdeleu
Are the limits set by the parameters FERROR and MIN_FERROR?
And if yes, what value can I use?

Please Log in or Create an account to join the conversation.

More
06 Jun 2019 20:08 #136086 by PCW
yes, and say 1 inch or 25 mm
so you will only get an error when you get beyond these limits

I would not suggest setting them much wider because of the possibility
of forgetting to reset them, and huge following error settings are a safety
hazard

Please Log in or Create an account to join the conversation.

More
06 Jun 2019 20:47 #136089 by Peterdeleu
Ok great!!, I was able to run the program.
If I measure the voltage on DRV1,2 and 3 (X, Y and Z-axis) I have 10V or -10V depending on the direction.

Is this always 10V? I thought that this was depending on the speed.
If I change the FEED OVERRIDE to 10%, it is still 10V. Is this correct?

Please Log in or Create an account to join the conversation.

More
06 Jun 2019 21:36 #136098 by PCW
The output voltage depends on:

1. The error
2. Your PID settings

If you set your PID tuning to all 0 except P=1, an error of one machine
unit will be 1V, so if the encoders are not connected, you will get an output
of 1V per machine unit moved

(assuming the default output scale of 10)

Please Log in or Create an account to join the conversation.

More
07 Jun 2019 08:42 #136184 by Peterdeleu
It looks scary to connect Mesa to the servo's mounted on the machine for the fire time.
It is probably wise to remove the servo's during a test run :)

Please Log in or Create an account to join the conversation.

More
07 Jun 2019 13:49 - 07 Jun 2019 13:51 #136203 by PCW
Absolutely, you should _expect_ runaways on initial testing, so if you can
its a very good idea to de-couple the motors from the linear axis.

Runaways are a lot less dramatic if the motor just spins at
full speed rather than breaking expensive parts or hurting someone...

This is also an important reason to have sensible following error limits
and have the drive enables working _before_ you connect the servos
to the linear axis.
Last edit: 07 Jun 2019 13:51 by PCW.

Please Log in or Create an account to join the conversation.

More
07 Jun 2019 15:13 #136208 by Peterdeleu
Next Question :)

I've added a 7i84 to the 5i25 - 7i77 set.
The connection has been done via a cut UTP cable.
The field power is also connected.
I ran the PNCconf again, after backing up my old files.
I was able to add the 7i84 card during the configuration. A 7i84 I/0 tab was added.
To see how the "name" was, I've configured a input (cycle machine) and a output (eStop on).
After this I've looked in the INI and HAL find for the changes I've made, and made the changes to the new INI and HAL file.
But now LinuxCNC will not start

The error message is:
Pin "hm2_5i25.1.7i84.0.2.output-00" does not exist.

What is my problem?

Please Log in or Create an account to join the conversation.

More
07 Jun 2019 16:19 - 07 Jun 2019 16:20 #136211 by PCW
Do you have VIN jumper in left position and both ( A and B ) 7I84 field powers connected?
Do you have 2 yellow and 1 red light on the 7I84 before you start?
Last edit: 07 Jun 2019 16:20 by PCW.

Please Log in or Create an account to join the conversation.

Moderators: cmorley
Time to create page: 0.121 seconds
Powered by Kunena Forum