Using 3 roboclaw, packet serial, USB

[quentin]

Could I use forwrard/home limiter to override the min max position of my motor/actuator?

How long would you say that a communication cable be? what I mean by that is: I have S1 (pull-up) connected to two S2... could one of these S2 (and its communication back to the master unit) be up to three meters (when robot arm is fully extended)? Currently it is the power and encoder cables that extend but I believe this set-up is damaging the roboclaw as the loads are heavy (although the robots moves slowly)

Would my robot and its design gain in simplicity from moving over to the ROS platform?

[quentin]

Also, what would I gain from plugging in a logic battery?

[Basicmicro Support]

Logic battery primary use is to prevent brownouts(high load causing low main battery voltage) of the main battery from causing a logic reset. In many situations this reset could cause problems.

A reset causes an autocalibration of zero in some RC and analog modes so if your control input was not at zero at that point in time the new zero would be wrong.

A reset takes time

A reset could cause the motors to act unexpectedly.

A reset would lose any temporary settings(eg if you set PID via packet serial commands in an arduino program but didnt write them to flash you would have to resend them but you may not know the Roboclaw reset due to a brownout.

Im sure I could list at least a few other reasons for a Logic battery.

The logic battery is only active when the Main battery voltage is lower than the Main battery. Basically think of it as a UPS for the motor controller.

[quentin]

quick question here: I want to make circuit schematics of my system. you have IGES files but I would like a 2D view to insert in the schematic rather than a 3D object (I am using AutoDESK eagle for the deed...). Is there any file schema you recommend I use to do a conversion?
Thanks!

[Basicmicro Support]

I do not believe we have anything of the sort. Usually you would jsut create a "black box" in your layout software and provide the appropriate connections.

[quentin]

Let me ask you this:

When I look at the current readings on ION MOTION and see that the current is say 5A while my motor is running. what happens then between the battery and the roboclaw? by that I mean what level of current is present there.

Now same question but with a current spike that is higher than the roboclaw's limit rating.

I have a motor that is supposed to deliver very short impulses to action a belt. it seems it has some stalling issues sometimes and I am trying to wrap my head around what is physically happening during those events.

Thanks.

[Basicmicro Support]

The motor current and the battery current are related by the current duty percentage. Motion Studio(if you are still using Ion Studio, update please) is reading the motor current. If the motor is pulling 5amps and the duty us 50% then the battery is sourcing 2.5amps.

When the Roboclaw sees current going above the limit it will automatically reduce the duty. When the current drops back down below the limit it will automatically increase the duty back to the user requested duty. It does this very fast.

It really doesnt matter what the battery current is. We measure motor current because that is what the mosfets see. Battery current will never be more than motor current and in the vast majority of cases is always less than motor current.

[quentin]

I am using the motion studio ha ha, sorry.
A quick question about the setup (as I am still trying to work on this over current issue that I am having)
When you set up the max currents on motion studio, do you enter 30A or 60A as MAX CURRENT values?
By default, they show up as 30A on each channel but do I have to explicitly change them to 60A or does the Roboclaw know to use both channels up to 60A from both max current being set at 30A?

[Basicmicro Support]

Max current on a 2x30A defaults to 60amps on each channel. That's the peak current limit.

P.S. if you are have a false current reading error you may need to adjust the current blanking percentage for that channel. They default to 5.4% which may be to small for some motors. Values can be as high as 20%. The symptom is false over currents at low duty cycles.

[quentin]

Hi,

Is there a way to force a speed limit on a Roboclaw through Motion Studio?
I have a motor installed on my system but I want to cap its speed at a value way lower than its QPPS and force it there so other users/developers that come after me may not mistakenly run that particular motor at a higher rate.

Also, Logic batteries must be connected to a backup battery source or can Power and Logic be coming from the same source (provided I don't let the batteries run low at any time)?

Thanks!
Quentin