Re:Mesa 7i77 differencial encoder connection.

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03 May 2012 11:09 #19752 by ishman
I have ordered some 5i25 + 7i77 plug-n-go bundle. I was going through the manual of 7i77 and saw that their encoder connectors have 8 pins for each encoder while my servo encoder provides 15pin connection.

My motor's encoder pins are as below.

12 Power supply(5V) +5V
13 Public ground 0V
1 Encoder A+ input A+
6 Encoder A- input A-
2 Encoder B+ input B+
7 Encoder B- input B-
3 Encoder Z+ input Z+
8 Encoder Z- input Z-
4 Encoder U+ input U+
9 Encoder U- input U-
5 Encoder V+ input V+
10 Encoder V- input V-
14 Encoder W+ input W+
15 Encoder W- input W-
11 Inhibit ground FG


While 7i77 provides following.

1 QA0 TO 7I77
2 /QA0 TO 7I77
3 GND FROM 7I77
4 QB0 TO 7I77
5 /QB0 TO 7I77
6 +5V FROM 7I77
7 IDX0 TO 7I77
8 /IDX0 TO 7I77

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03 May 2012 11:53 #19754 by BigJohnT
Does one set go to the drive and one set to the controller?

John

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03 May 2012 12:39 #19756 by ishman

Does one set go to the drive and one set to the controller?

I am afraid I don't know! The whole connection comes through a multi-cored cable and goes directly to the driver via serial cable type connector. But from Driver's output, there is A+,A-,B+,B-,Z+,Z- and GND and ZOC. Total eight connector output they provide.

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03 May 2012 12:48 #19757 by ishman
John !
I think it's the same thing as you asked. driver provides one set of output to controller. But is it a good idea to take feedback from driver ? and not from encoder directly ?

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03 May 2012 14:07 #19759 by BigJohnT
If the driver provides the A+A-, B+B-, Z+Z- for the controller it makes sense to use it. I guess it makes the wiring neater that way.

John

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03 May 2012 14:10 #19760 by PCW
The drive needs the U,V,W wires for motor commutation. Its probably best to use the drives A,B,Z outputs so you dont have to "tee" any signals. Depending in the drive, these encoder outpus may just be buffered copies of the encoder inputs or they may be scaled by the drives DSP.

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03 May 2012 14:32 - 03 May 2012 15:15 #19761 by ishman
I appreciate you all ! Thanks.

Now it becomes clear that I should use drives output as an encoder feedback.

Thanks again.
Last edit: 03 May 2012 15:15 by ishman.

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03 May 2012 15:05 #19762 by BigJohnT
I love it when a plan comes together...

John

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03 May 2012 18:52 #19782 by andypugh
ishman wrote:

1 Encoder A+ input A+
6 Encoder A- input A-
2 Encoder B+ input B+
...
9 Encoder U- input U-
5 Encoder V+ input V+
10 Encoder V- input V-


ABZ are the encoder lines, 1000+ pulses per rev. Incremental quadrature + Index
UVW are the Hall sensors, 6 unique patterns per rev, low resolution but absolute position.

ABZ are used for positioning, UVW purely so the drive knows which coils need power as the motor rotates.

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03 May 2012 19:13 #19784 by ishman

ABZ are the encoder lines, 1000+ pulses per rev. Incremental quadrature + Index
UVW are the Hall sensors, 6 unique patterns per rev, low resolution but absolute position.

ABZ are used for positioning, UVW purely so the drive knows which coils need power as the motor rotates.

Wonderful information. I appreciate your knowledge andypugh.

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