SDC2130: Strange encoder feedback

4 years 8 months ago #29531626 by nabilgabbouj
Dear all,

I have the sdc2130 unit connected to a DC motor rated at 3000 rpm and an AMT102-V encoder configured at 2048 ppr.
In closed loop speed the motor runs smoothly, however at a certain speed (approximatly 800 rpm) the encoder feedback turns negative and decreases. And the motor goes rapidly backwards and forwards and then it stops (because of the loop error detection).

I enclosed the chart for the tests we did in open-loop.

After reading the SDC2130's datasheet I thought that the problem was the encoder pin frequency, so I changed the PPR in the encoder to 125 PPR. The problem persists. I already updated the firmware of the unit.

What should I do?


File Attachment:

File Name: ChartLog.txt
File Size:59 KB
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4 years 8 months ago #29531632 by niko
Hello,

Please provide us with a chart log with the following values:

Motor Command 1
Counter 1
Speed 1 RPM
Feedback 1
Loop Error 1

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4 years 7 months ago #29531654 by nabilgabbouj
Sorry for the delay,

I've attached the logs that I've done with the unit with the values requested.

Thank you in advance,
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4 years 7 months ago #29531662 by niko
Hi,

from the data I can see that the encoder counter is missing counts. Which version of SDC do you use (check the label on the board)? What is the PPR/CPR of the encoder?

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4 years 7 months ago #29531664 by nabilgabbouj
I am using the SDC2130 with 2048 PPR encoder.

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4 years 7 months ago #29531665 by niko
Please type ?uid and send me the result.

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4 years 7 months ago #29531666 by nabilgabbouj
?uid
UID=100:1042:108134224:1381336679:1730167605

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4 years 7 months ago #29531670 by niko
Hello,

Well since you have the SDC2130 v1.4 there is a limitation in encoder frequency. According to datashhet the maximum frequency is 30000 Counts/sec. This is due to the fact that the encoder is a sof encoder. If you use only 1 motor channel you can install the SDC2130S firmware. In that case the encoder is a hard encoder and the max frequency is 1M Counts/sec.

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