ethercat xml file configuration

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04 Nov 2021 09:22 #225214 by wang
hi guys
I have a few questions about ethercat xml file configuration
 

What are the meanings of these parameters and how should I configure them? Can anyone tell me or give me a connection? I want to see the official explanation

I have successfully controlled the device through Ethercat, but I am not clear about the meaning of these parameters. I think that if you want to reduce the Ethercat cycle and improve the performance of the machine tool, you must understand their true meaning.
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04 Nov 2021 11:22 #225226 by db1981
hi,

i will try to explain it with my (coding) english....

appTimePeriod
This is the time in nano seconds at which the rt part of ec master is called (read/write) this has to match the period of the thread in which you are calling
the ec-read-all and ec-write-all functions (example: servo-thread)
This value will be internaly passed to the ec_master domains and dc functions for clock checking and calculations.
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04 Nov 2021 11:40 - 04 Nov 2021 11:40 #225230 by db1981
refClockSyncCycles:

This is part of the DC Clock mechanism in ethercat.
To get knowledge of DC Clock System you can read the Ethercat Standard or the
IGH Etherlabmaster manual.

in short:
Every Slaves with implemented DC Clock runs its own clock. Due the manufacturing differences the timers newer run 100% identical. So there is a
little drift in the DC Clocks. For drift compensation the master sends an Master Clock sync signal and the slaves will sync their clocks again.

refClockSyncCycles specifies after how many appTimePeriods this is done.

If you do it everycylce (1) your average jitter in the whole system could be high (depending on the master hardware) so this value should not be to high to smooth the jitter, but not to low to get the Clock Drifts to high ....


If you got very accurate EC-Slaves like SoE Drives you can get Problems with not getting an accurate enough DC-Timming for this Slaves.
If this happens you can use another method of DC-Clock implemantion. You have to compile linuxcnc by yourself and install the add_task_pll_functions patch.
After this an value <0 in refClockSyncCycles will switch to "Slave synchronisation" Mode.
The Masters apptime will be synced to the first slaves clock in the bus. this is done by finetuning the master apptimeperiod and the linuxcnc-thread from cycle to cycle. (pid)

 
Last edit: 04 Nov 2021 11:40 by db1981.
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05 Nov 2021 01:20 #225323 by wang
I’m using Google Translate, and I’m very sorry for the incompatibility of the sentences produced by the translation.

Thank you very much for your patient teaching

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