Futaba SBUS & Brain FailSafe failure

[smeggy]

Hello folks.

On another part of the forum, I asked why the failsafe doesn't work when using a Futaba S-Bus output and an MSH Brain.

I have checked for clues as to what is going on by monitoring the S_BUS protocol with a scope.

I can see the desired "failsafe" value (set up from the Tx) is indeed taking effect on the appropriate channels, at just over 1 second after the Tx is switched off.

Good!

I can also see the "failsafe" bit ('flags' byte) is going from 1 to 0 (inverted) at exactly the same time (just after 1 second after the Tx is switched off)

Reasonable!

However,

I can also see there is a "Frame Lost" bit ('flags' byte), which is going from 1 to 0 (inverted) almost immediately after the Tx is switched off (in sympathy with the red LED on the Rx). The delay between the "Frame Lost" and the "failsafe" bits changing is seemingly 1.0 seconds.


So I would guess the Brain is seeing the "Frame Lost" bit and then simply 'hold's the previously live channel values, hence ignoring the subsequent failsafe setup of the radio.

Assuming my guess is correct, I think that process is flawed.
Can any Brain experts comment? How can this be fixed? I hate not having a failsafe when flying.

[smeggy]

I've emailed Bill of MSH Direct. He wasn't aware of any problems with this; he is now

[kingmeow]

Any updates on this? I'm trying to use failsafe using an 8FG and SBUS. I see I have three places to program this; Tx, Rx, and Brain(?) My ESC goes to the Brain, nothing goes to my Rx (other than connection from Brains to Rx).

[kthane]

Doesn't work with Spektrum either. I think they are well aware Ikon/Brain will hold last servo position except throttle which will go to zero. I would have preferred idle on my nitro. Been schooled on RR; Futaba is bullet proof!

[kingmeow]

So you're saying to just set up failsafe on the 8FG Tx and don't even bother with the Brain?

[kthane]

May want to verify throttle goes to 0 when you turn TX off, but other then that, yes, that's what I'm saying.