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Topic-icon SDC2130 v1.5: Brakes released only after a few seconds delay or never

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6 years 5 months ago #29528468 by sd1074
After encountering this issue , we've got a new motor controller. Now it's SDC2130 v1.5, firmware v1.2 RCB100 05/25/2013.

We have two motors, each with a motor brake. When I started to test brakes, I noticed that when I manually (via Roborun+) activate (=release) a brake, the Digital Output indicator in Roboron+ turns on, and the brake gets released, as expected, but when I then deactivate (=engage) a brake, the Digital Output indicator immediately turns off (again, as expected), but the brake is disengaged only after a few other seconds, or sometimes it doesn't get released at all. Or it may get released when another brake state is changed. This behavior is kind of unstable. Sometimes one channel works perfectly, but another channel has a brake delay. Sometimes both channels have a delay.

In the current, config BKD=250
The battery voltage as measured on the motor controller with a multimeter when both motors are off is 25.5V (Roborun aslo reports ~25.5), and the motors are on is 25V (Roborun reports ~24.7).

The motor controller is new. We plugged it to an existing system which was used for almost 2years with SDC2100 v1.4. We did not experience this brake delay problem with the previous board.
Everything else (open-loop mode, closed-loop mode) seems to work fine.
I tried a config file we used on our previous motor controller, and I also tried to reset to defaults and then do minimal changes to enable brakes. Both files are in the attached zip-archive.

Could you please help?
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  • Griffin Baker
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6 years 5 months ago #29528469 by Griffin Baker
So in one of the file configurations, the digital outputs are set to on; when: never. The other is set for when digital output turns on active high; When: motor 1 is on, digital output 1, and motor 2 is on, digital output 2.

I take it you are engaging and disengaging these outputs through the run tab.

I'll try to replicate this situation here if I can.

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6 years 5 months ago #29528470 by sd1074
Yes. PrevioslyUsedConfigWithAutoBrakes.xml is what we use on our robot. In this config brakes are configured to turn on and off automatically.

DefaulConfigWithMinimalChangesToEnableManualBraking.xml is the default config, with minimal changes to enable manual brakes. I was using it to manually turn off and on the brakes via Roborun to debug the issue without starting motors.

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  • Griffin Baker
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6 years 5 months ago #29528471 by Griffin Baker
Wasn't able to replicate the same problem. Here is what I did. Granted I have 2 very small motors that I've wired to my digital outputs 1 and 2. I set the digital output 1 to active when: high, and activate when: never. I did the same with digital output 2.

I did a quick reset to defaults.

I went into the run tab and tested them out. I turned on digital output 1 and the motor spins. Click on the digital output again to turn it off, and motor stopped spinning. I then repeated for digital output 2.

I went back into the brake delay settings as the defaults are set to 250mS.

I changed this value from 250mS to 1000 (1 sec) and repeated the test. After disengaging the digital output, there was a 1 second delay before the motor stopped spinning. Same thing occurred with digital output motor.

Have you tried changing the brake delay to 0 or any other values?

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  • Griffin Baker
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6 years 5 months ago #29528472 by Griffin Baker
Could you upload a wiring diagram of your brake setup on the digital outputs. If the digital output indicator led turns on and off as expected, then it seems it might be in the wiring.

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6 years 5 months ago #29528473 by sd1074
Yes, I have. Tried 0, tried 100. No noticable change.

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6 years 5 months ago #29528474 by sd1074
I'll do the wiring diagram. The thing is: no wiring was changed, it's the same as it was before replacing the motor controller.

I can also try connecting the old motor controller again.

Also, I am not an electronics guru, but I know DOUTs are open collector, and I can't just measure the output without brakes. How can I test those outputs without connecting the brakes?

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  • Griffin Baker
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6 years 5 months ago #29528475 by Griffin Baker
You can wire up an led on the outputs. Provide the small required voltage to the led, and wire up one end of the led to the digital output.

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6 years 5 months ago #29528476 by sd1074
Zipped wiring diagram is attached.
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6 years 5 months ago #29528484 by sd1074
OK, I've just tested it with an LED. The LED works perfectly. Maybe something is wrong with the brakes. Maybe they are overmagnetized or something like that.

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