4 ms·

So how do you prevent them from grabbing the wrong break out box? Like say they have one that is setup to test the motor driver circuitry and another one that

So how do you prevent them from grabbing the wrong break out box? Like say they have one that is setup to test the motor driver circuitry and another one that is setup to test the motor? Or say the breakout box intentionally has both sides of the connection on it, so that you can get in-between the driver and motor?

amluto 3y ago
I can think of very few kinds of connectors for which this type of error is even possible. You would need two cable terminations which can connect to each other, for which either side can plug into the same jack. So either the ends are literally the same (e.g. Anderson Powerpole), or there is some kind of weird symmetry or inadequate keying. Or maybe the two cables don’t connect directly and instead go through some of kind of interface? The latter is fairly common in networking, e.g. “feed-through” patch panels and keystone jacks and quite a few kinds of fiber optic connectors. All of these seem like utterly terrible ideas in an application where you would take the thing apart after final assembly and where the person doing the disassembly or reassembly could possibly access the wrong side of the panel.
- maxerickson 3y ago
  A break out box could very sensibly have both sides of the connector on it and then have the various pins broken out into individual connections for flexibility. In that case keying or whatever isn't going to prevent you from connecting to the wrong side, because both sides are present.
- jeffreygoesto 3y ago
  One guy in our workshop had to provide DC to a display with a round 4-pin connector. He soldered two neighboring pins to Gnd and the other two to Vcc. There were two chances to short the powersupply, one to brick the display and one to get it right. Guess what we had to replace until we found out.
numpad0 3y ago
Looks like the author tried to double-power the motor with both the spacecraft motor driver and through the breakout box that MITMs the driver and the motor. In such event, the free-wheeling diode in the driver will allow reverse current to be fed back to the driver's power supply up to certain amounts. This will absorb back-EMF, or energy from "regen" from the motor. I'm suspecting the breakout wasn't literally sitting between the driver and the motor, but rather all internal connections are broken out to the box for testing; and likely the author's mistake was to not mess with the spacecraft to temporarily disconnect the driver. But I'm not sure if I'd "just" made the right call and done so nonchalantly on a Mars rover to launch in few weeks.

amluto 3y ago

I can think of very few kinds of connectors for which this type of error is even possible. You would need two cable terminations which can connect to each other, for which either side can plug into the same jack. So either the ends are literally the same (e.g. Anderson Powerpole), or there is some kind of weird symmetry or inadequate keying. Or maybe the two cables don’t connect directly and instead go through some of kind of interface? The latter is fairly common in networking, e.g. “feed-through” patch panels and keystone jacks and quite a few kinds of fiber optic connectors. All of these seem like utterly terrible ideas in an application where you would take the thing apart after final assembly and where the person doing the disassembly or reassembly could possibly access the wrong side of the panel.

maxerickson 3y ago
A break out box could very sensibly have both sides of the connector on it and then have the various pins broken out into individual connections for flexibility. In that case keying or whatever isn't going to prevent you from connecting to the wrong side, because both sides are present.
jeffreygoesto 3y ago
One guy in our workshop had to provide DC to a display with a round 4-pin connector. He soldered two neighboring pins to Gnd and the other two to Vcc. There were two chances to short the powersupply, one to brick the display and one to get it right. Guess what we had to replace until we found out.

numpad0 3y ago

Looks like the author tried to double-power the motor with both the spacecraft motor driver and through the breakout box that MITMs the driver and the motor. In such event, the free-wheeling diode in the driver will allow reverse current to be fed back to the driver's power supply up to certain amounts. This will absorb back-EMF, or energy from "regen" from the motor. I'm suspecting the breakout wasn't literally sitting between the driver and the motor, but rather all internal connections are broken out to the box for testing; and likely the author's mistake was to not mess with the spacecraft to temporarily disconnect the driver. But I'm not sure if I'd "just" made the right call and done so nonchalantly on a Mars rover to launch in few weeks.