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 Post subject: Inconsistent motor performance
PostPosted: Wed May 28, 2014 8:51 pm 
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Joined: Wed May 28, 2014 8:36 pm
Posts: 8
Hello,

I am having trouble getting my motors to be in sync and consistently firing. I am using a Roboclaw 2x60A with two FIRST CIM 12v DC brushed motors and I am using two 12 volt 100 amp PowerMax power supplies that are running in parallel to increase the amperage. (http://powermaxconverters.com/pm312volt.html) At first, I was using one of the power supplies, but the motors were not getting enough juice. Currently, they are working great about 80% of the time. I am controlling them using an Arduino Mega 2560 too.

Each motor is attached to its own channel. Is it safe to run the two motors off of the same channel on the RoboClaw? I wanted to check before I go burning up the motor controller or setting my project on fire.

Also, any ideas why I would be getting inconsistent performance? It's difficult to explain the project I am working on, but the best way I can describe it is a large catapult. The motors fire very quickly for a short amount of time.

Thanks for any help or advice!

- John


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 Post subject: Re: Inconsistent motor performance
PostPosted: Wed May 28, 2014 9:09 pm 
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Joined: Wed May 28, 2014 8:36 pm
Posts: 8
If I run the motors in series do I still use both channels also?


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 Post subject: Re: Inconsistent motor performance
PostPosted: Thu May 29, 2014 3:36 pm 
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Joined: Wed May 28, 2014 8:36 pm
Posts: 8
Ok so I am currently running the motors in parallel, but that cut the amps in half. I need to fire both motors using one Arduino pin. I tried making a Y connector going from a digital Arduino pin to the S1 and S2 pins on the RoboClaw, but that did not seem to work because I got no response. Any ideas? Hello?


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 Post subject: Re: Inconsistent motor performance
PostPosted: Tue Jun 03, 2014 7:58 pm 
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Location: Temecula, CA
If you are using an arduino already I suggest using packet serial with a Mixed command to start.stop both motors at the same time. Note that the motors speeds will still not necessarily match. With out feedback(eg encoders) the motor controller has no way of compensating for motor differences.

As for the Y adapter cable, we have never tested something like that. When I have a chance I will check it to see what could be happening.

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 Post subject: Re: Inconsistent motor performance
PostPosted: Tue Jun 03, 2014 9:06 pm 
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Joined: Wed May 28, 2014 8:36 pm
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Do I just wire it the same as shown under Simple Serial in the user guide? Also, can you send me an example of a mixed command to fire both motors at the same time?

Thanks for the help!

- John


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 Post subject: Re: Inconsistent motor performance
PostPosted: Tue Jun 03, 2014 10:03 pm 
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Joined: Wed May 28, 2014 8:36 pm
Posts: 8
Nevermind. I found the diagram. I was unable to get the Packet Serial mode working :( I used the example code too.

What does "RoboClaw roboclaw(5,6);" do? Does that mean channel 1 is on pin 5 and channel 2 is on pin 6? So S1 should goto pin 5 and S2 should goto pin 6? Also, I keep getting power errors when I plug VCC and Ground from Arduino into the RoboClaw.

Last ditch effort....

I see that Simple Serial has one I/O wire, but still has two channels/motors. Would that solve my problem of firing the motors at the same time with one command?

- John


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 Post subject: Re: Inconsistent motor performance
PostPosted: Fri Jun 20, 2014 5:15 pm 
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Joined: Thu Mar 01, 2001 7:00 pm
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Location: Temecula, CA
Packet Serial uses 2 pins, one to transmit and one to receive data. S1 is the pin you send commands to the roboclaw with and S2 is the pin you receive it back from. The init function, Roboclaw roboclaw(5,6), is telling the arduino that pin 5 will receive data back from the roboclaw and pin 6 will send commands to the roboclaw. Please read the manual section on packet serial.

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 Post subject: Re: Inconsistent motor performance
PostPosted: Fri Jun 20, 2014 6:49 pm 
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Joined: Wed May 28, 2014 8:36 pm
Posts: 8
I got it to work. I had something wrong with my code. Thanks man.


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