[etherlab-users] Distributed Clock with Yaskawa SGDV drives

[Graeme Foot]

Hi,

 

I'm having a problem with my Yaskawa SGCV drives.  I am using them with Cyclic Synchronous Position Mode.  The problems is that while moving they frequently get an unstable position error.  The unstable position errors last for about ¼ of a second and occur regularly every 4 (approx) seconds.

 

The position error is always less than the cycle delta position.  I am setting up the drives to use the distributed clock but I am suspecting that something is not set up correctly and the position error is occurring due to a drift in cycle relative to the master.

 

 The "DC system time transmission delay" (from the "ethercat slaves -v" command) for the drives are:

drive 1 (slave 9): 2147486148 ns

drive 2 (slave 10): 2147487218 ns

They are being reported as 32bit distributed clocks.

 

 

When doing the "ethercat reg_read -p<slave> -tint32 0x092C" command on each of the slaves then the slaves prior to the yaskawa drives get numbers such as:

0x00000010 16

0x00000024 36

0x80000011 -2147483631

0x80000004 -2147483644

 

Where the low order bytes contain low numbers but the sign bit may be on or off.

 

However, the yaskawa slaves are more like:

0x66a32ed9 1721970393

0x669f8483 1721730179

0x669d0223 1721565731

0x669b553f 1721455935

 

 

If I disconnect the drives then the rest of the slaves still behave the same (where the sign bit may be on or off).

 

 

Does anyone have any ideas what I should be looking at next?

 

 

Regards,

Graeme Foot

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