V5 Backwards Compatibility

@Roboter Hersteller writes “What Cortex materials will be backward compatible for the V5 system? Will you be able to use the sensors and 393 motors or will will all electronics need to be upgraded?”

@VEX Support “Technically you will be able to use the legacy sensors, 393 Motor, Motor Controller 29 & Power Expander.
However please check the Game Manual to verify if they are competition legal.”

So this answer is correct, but it needs to say “legacy sensors” and “a Power expanded driving a Motor controller 29 and Motor 393”. The power rail on the 3 pin ports are not enough to drive the 393 motors but the combo of the Power Expander, battery and the other stuff is. So far the motor expander and motors have not been mentioned.

Just wanted to be clear based on what we’ve seen and has been written by VEX says this in other places.

This is my understanding, which has been corroborated by several posts on this forum as well as the Turning Point Game Manual.
If the question is: “Will you be able to use the sensors and 393 motors or will will all electronics need to be upgraded?”
The answer depends on what you are using the V5 system for.
The legacy sensors will work, for the most part (all but the flashlight, I think), with the V5 brain. There are 8 legacy 3-wire ports on the V5 brain. However, they run on a 5-volt bus rather than the 7.2-volts that the Cortex provides. You can run the 393 Motor with motor controllers from those ports as well. Again, understanding that they are running at a reduced voltage. As for running the 393s from the V5 through a power expander, I have heard one person say that they were able to do that. They did not elaborate on their results.
That being said, for competition, the 393s are NOT legal if you are using V5, regardless of how you have them connected (per the Game Manual). The legacy sensors will be legal however.

There are LOTS more Cortex systems out there in classrooms than there are in VRC/VEXU. Those people are interested in being able to use older things (sensors, motors, etc) with their V5.

Every sensor / motor from Cortex is usable in the classroom with V5, except the flashlight . The motors are power limited so using 1 at a time is suggested for the time being.

I expect we will come out with more accessories for V5 after the initial launch so that classrooms and competition teams can make use of their old sensors.

@Foster We tried two 393 motors on V5 legacy ports. The current limiter kicked in when the motors were simultaneously commanded from 0 to 127. Ended up reducing one initially so it wouldn’t trip out.
You could successfully run >1 motors provided they have slew rate limiting and prevention from mechanical overload. Perhaps the legacy port current limiter filter bandwidth could be reduced without causing any harm.

Adding a power expander with associated 7.2V battery is messy and unless you already have plenty kicking around just buying more V5 motors would make more sense. Can’t see that ever being competition legal either.

To truly support 393 motors you’d probably need a V5 port accessory that powers 2 (3?) motors at 7.2V with soft current limiting per motor rather than the 5V legacy port hard current trip (well in current firmware anyhow). Hopefully that’s what @Paul Copioli is eluding to.

That is taken care of in the next release of vexos, we will have a new legacy motor class in VCS that will slew rate limit the 393 motors and solve that particular issue.

EDIT//: [Question Reverted Because I Didn’t See The Responses Above]

The port expander is messy, but it works. Not legal for competition, but for a classroom it works.

There are going to be a huge number of motor expander available in a few months, give them to your schools. It’s also a good thing for students playing with ardunios.