Answered: Y-Cable on power expander

[David_Frykberg]

Rule <R12> clearly states:

<R12> A maximum of one (1) VEX Y-cable can be used per Motor Port of the Microcontroller or Power Expander. (You cannot “Y off a Y” to have more than two (2) motors controlled by the same Motor Port.) a. Teams using the VEX ARM® Cortex®-based Microcontroller can only power one (1) 2-wire Motor per each of the two 2-wire motor ports on the Microcontroller. It is illegal to “Y” off a 2-wire Motor Port.
b. Teams may not “Y” off a Motor Controller 29

We understand the intent is to prevent overheating and potential fire hazard?

We know from <R12> that it is legal to connect a Y-cable to each port on the Power Expander.

We also know that a 3-wire Y-cable from the Cortex to the Power Expander is legal (it’s essentially only a control wire controlling two Expander ports)

From logical extension of above, we assume therefore that it is legal to connect, say, Motor Port-2 to Expander PortA-in and PortB-in, and then to connect Expander PortA-out to motor controller 1 and to motor controller 2 via a Y-cable.

Please confirm that this is legal, or if not, why not. Many thanks.

[DRow]

I’ve moved this thread to the official Q&A.

[Karthik]

From logical extension of above, we assume therefore that it is legal to connect, say, Motor Port-2 to Expander PortA-in and PortB-in, and then to connect Expander PortA-out to motor controller 1 and to motor controller 2 via a Y-cable.

Please confirm that this is legal

Yes, this is legal.