Active or passive MXP board?

[Steve Garward]

Understanding the definitions and rules given on the blog are preliminary, we have the following question:

If an expansion board breaks out the MXP pins (including PWM pins) to be used, servos will require a supply voltage to actually work. If we were to add a voltage regulator circuit to the board (input voltage from PDP), and the regulator output was fed to pins such that the servo would be powered, would this classify the board as active or passive?

In this case, the MXP PWM pins are broken out directly - no circuitry interrupts the flow from MXP to header pins on the board. Our reading of the given preliminary definitions are rules would say this is a passive device.

[Kate]

Based on what you’ve described, that would be an Active Device. It doesn’t matter why the active components are on the board or whether they’re upstream, downstream, or part of the interface between the roboRIO’s MXP and the board’s header pins. As soon as the board’s functionality is beyond conduction and/or static regulation of the electrical energy applied to it (e.g. wire, splices, connectors, printed wiring board, etc.), it’s not a PASSIVE DEVICE anymore.

[Steve Garward]

Even though the power regulator circuit is not upstream, downstream, or inbetween the MXP pins themselves and the boards header pins?

This would mean a team can use a passive board to interface with motor speed controllers (which don't require power), but would have to buy/make an approved active device board to use the MXP pins to control servos. Is this correct?

[Kevin O'Connor]

Steve, that's correct. The 10 on-board PWMs could be used to control servos or an approved ACTIVE DEVICE.

[jross]

Based on what you’ve described, that would be an Active Device. It doesn’t matter why the active components are on the board or whether they’re upstream, downstream, or part of the interface between the roboRIO’s MXP and the board’s header pins. As soon as the board’s functionality is beyond conduction and/or static regulation of the electrical energy applied to it (e.g. wire, splices, connectors, printed wiring board, etc.), it’s not a PASSIVE DEVICE anymore.

I'm confused about the reference to active components upstream/downstream. Does this mean that plugging an encoder (an active device) into a passive MXP makes the MXP active?

[Kate]

jross, Yes, the current wording does say that - but we want to find a way to accommodate encoders and other helpful components that would fall in to the Active Device category, couldn't be a hindrance to a Disable command, and would be quick/easy for Inspectors to verify. We'll work on this more.