In article ,
says...

On 2019-07-16 10:58, Greg (Strider) Moore wrote:

JF: Here's the thing (and Jeff and Fred will correct me if I'm wrong) but
believe it or not, redundancy is NOT always better.

There is almost certainly redundancy in sensors (such as the SSME's had)
because you don't want a flakey sensor triggering an abort. BUT, once the
decision is made, you want it as simple as possible a single wire with
voltage is that simple.

Then you need 3 wires to confirm to the other stages that a command to
abort is being sent instead of just a flaky connection due to vibration
that is causing voltage to drop on that analogiue line.

You're conflating redundancy in sensors vs. a wire used to send a
command.

YouLll notice that the SpaceX documents speak of "command". A command
sent as data would have checksums etc to valiate it, and likely sent on
at least 2 data links across modules.

You're assuming that there is some sort of data link here. That is
almost certainly not the case because this system needs to be as simple
as possible. One GTFO "command" is all we need, so a discrete command
line is what they would use.

Everything else that followed the above was based on these false
premises, so I deleted it all.

Jeff
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