Does the Spark Max Data Port Breakout change the pinout itself (so I can connect a data cable from a CTRE Mag Encoder, etc.) or do I need two breakout boards for it?
The data port connector on the breakout board is passthrough with respect to the data port connector on the Spark Max. The pinouts on the two connectors are the same.
It looks like you recognize that an “alternate encoder” mode is needed for the Spark Max if using an external encoder in brushless mode. Please consult the Spark Max docs for the data port pinout in alternate encoder mode. It’s not the same as the standard pinout.
To add on to the previous post, the SRX 10 pin ribbon data cable will work fine plugged directly into the Spark Max if you don’t want to use the breakout board, but you need to be careful with what it is connected to at the other end. If the device at the other end has all 10 pins, it may be setting continuity to ground on some of the pins that you are not using for the encoder and this can mess up the signal from the motor encoder.
We found that we needed to cut the wires on the ribbon strip for all the pins except the pins we were using for the encoder. We were using the analog encoder signal so we had to cut all the other wires except for the GND, +5V and Analog In in order for the motor controller to work. We were working with the Lamprey hollow bore encoder. I am not sure if you will have the same issue with the CTRE mag encoder or not.
This may be eaiser to do using the breakout board you showed. We did not have any issues just clipping the wires in the ribbon.
Rev was very helpful in working with our programming team to integrate the motor controller with the encoder. You may want to reach out to them if the documentation is not clear on how to work with the specific device you are using.