Hello,

Please provide more detail to your question so we can help you

I think, I see what is going on. I am using a VEX 393 3-wire motor from the modified servo control in the EZ-B. The pulse width from the EZ-B for Reverse is 0.5mS, independent of the value that I enter in the config window. VEX uses 1.0 mS for reverse. Their motor controller 29 units can deal with the narrower pulse width.But, their motors can not. It appears that I am stuck with an incompatibility issue.

I have a lot of VEX parts that I spent a fortune on. I am trying to help these guys complete their robotics project by giving them some of my parts, since I have parts but not cash. Hmmmmm.

Is there a way to stretch that reverse pulse width by a command?

Thanks again

Hello,

Every control has a CONFIG button which opens a config window. Within the Modified servo config, you will find values to configure for each direction of both channels (left and right). The values are Forward, Reverse and Stop. A checkbox will send a PWM for STOP rather than sending no PWM (which is default).

Use the values in the CONFIG menu to select values that work for your hardware.

@Troop191Robotics Are you referring to the "Modified Servo" control or the "Modified servo Movement Panel" control?

I don't think it is really an issue with the EZ-B so much as the semi-proprietary nature of the VEX components.

With regards to what you might be running into, I did read somewhere the the VEX servos & motors (with their controller adapter) have a higher voltage range of 5.5 - 9 volts and thus may not work well with typical servo controllers without first supplying external voltage to the motor and running just the signal wire to the controller (and common ground between controller and servo power)... try that with your setup.

Good clarification Gunner, I am talking about the modified servo control NOT the Modified servo Movement Panel. Its config window only accepts values for Forward and Revers. Regardless of what value I put in for Reverse, I maesure 0.5 mS pulsewidth.

As to the operating voltage for the VEX motor controller, I am using a regulated 8 Vdc. Thanks, that's important. I monitor it with a panel meter. it is well behaved.

Thanks guys

Wow, do I need a spell checker!

Anyway, I just ran into the same issue when I tried to drive my Fergelli linear actuator in the servo mode. It would not reverse. So, I ran it in the PWM mode.

Just some more info

@Troop191Robotics I don't have any VEX servos to test this with, but based on my limited oscilloscope experience (AKA zipity squat) I can see the 0.5mS reverse and 2.5 forward pulse... so out of curiosity I used the PWM control and I can get to 1.0mS at about 5% setting.

Try playing around with the PWM and then possibly running your VEX servos using a scripted preset PWM setting and see if you can control them that way.

Disclaimer... I am really pulling this one out of my... hat and would be interested in your results.

@DJ, when I am playing around with the modified servo control and watching the scope, I do not see any changes when adjusting the config values... what are they supposed to do in this particular control?

Strange... I posted my above little bit then got an email of a new post a minute later and there is yours, but showing from about 30min earlier (yet I didn't see it when I posted)... Alas, you already figured out the PWM without little old me silly timewarps