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AKD with EtherCAT - Position actual internal value 0x6063

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Hello all

I am new here to the KM community

We are a machine tool builder of Ultrasonic cutting machines

www.agfm.com

We are starting up a new machine with KM AKD drives with EtherCAT

AKD-P04807-NBCC-D000 

We are using the Balluff BiSS-C measuring system readheads and scales.

BML-S1G0-B7ED-M5EA-D0-S284

BiSS-C 32 bit

 

I am reading the "position internal actual value" over ECAT via 32 bit object 0x6063

I am having a problem with the sign changing in the ECAT variable.

On the Feedback1 screen in Workbench, the sign does not change.

The scale is ~14000 mm long

At position X3070...the sign changes to negative.

It keeps counting positive until it reaches +3070 and sign changes again.

I have already performed a "preset" on the reader to set it to 0 at the most MINUS end of travel.

If I push the axis by hand,  Workbench Feedback1 screen counts correctly to 14000

In X10 feedback screenin "Linear encoder resolution" is set to 24000

"BiSS sensor bits" is set to 32

In ECAT at the address 0x6063, the the sign of the counts is changing

I think I need to reduce the number of pulses to the ECAT variable.

Anyone know how to do that?

 

Mr. Kenny Hampton has been to American GFM and worked with me on another project with an S712 drive.

We are in Chesapeake, VA

 

Thanks for any help u can provide.

 

Steve Phelps

Sr. EE

 

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2 Answers

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Thanks very much Martin for that answer.
I already figured out with the help of others that FB1.PSCALE was the answer.
It was set to 24 which caused the rollover.
I have reduced it to 20 and the rollover is now solved in the whole 14 meter stroke.

 

Also, that link you provided with more info was very helpful for me to use in the future.
This is a great community
SP

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Hi Steve Phelps,

There are two things to your question.

First the position in the drive (visible via workbench).

If this position is correct the setting of the feedback is ok. So the BiSS Bits and the feedback setting should be ok. If I understood your question correct this is the case for you.

Second the position in the master (read via EtherCat)

The position 0x6063 has only 32-Bit for turns and number of turns, while the drive has 64-Bits. (Let me use turn here, for linear axis a turn is equivalent to a pole pitch or magnet width.) This means there is a reduction of resolution done when mapping the internal position to the Ethercat variable. The default value is 20-Bits per turn and 12-Bits for number of turns. If the number gets bigger than that a rollover happens and the position number of turns starts at the biggest negative value to further increase.

A Master could take care of this by only monitoring the change and not the absolute value and map this into a bigger variable (e.g. 64-Bit) like in the drive.

Or the resolution per turn could be reduced to have more bits to count number of turns. This happens in the drive by setting FB1.PSCALE. Some more information about the scaling can be found at this link.

https://www.kollmorgen.com/en-us/developer-network/position-scaling-akd-drive-ethercat-communication/

 

Regards,

Martin

Comments

Thanks very much Martin for that answer.
I already figured out with the help of others that FB1.PSCALE was the answer.
It was set to 24 which caused the rollover.
I have reduced it to 20 and the rollover is now solved in the whole 14 meter stroke.

Also, that link you provided with more info was very helpful for me to use in the future.
This is a great community
SP

StevePhelps - Wed, 08/28/2019 - 03:20
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