Opinions on throttle direction changes while moving?

[NtheBasement]

This bothered me enough to look into it further.  Still a mystery.  One thing; I wrote that I was using program on main, but really it was use programming track (no other locos on the layout) when setting and checking CV4. 

I have two throttles, a PowerCab and a ProCab.  I unplugged the ProCab and got the same result.

Tried leaving CV4 at zero, setting momentum and checking.  No change, CV4 is still 0.

Not that it should make a difference but PowerCab version is 1.65, CV29 is 38 so no speed table, and decoder is a DZ126.

Clueless.

[peteski]

Odd... exactly the opposite of what I observed!  Need one of those packet sniffers.  I've also wondered what emergency stop does if the decoder has momentum set.

I have packet analyzer, but in this case is is not needed as the behavior can be observed by how the loco behaves and by reading out values of CV3 and 4. Plus the manual also explains it.

[peteski]

This bothered me enough to look into it further.  Still a mystery.  One thing; I wrote that I was using program on main, but really it was use programming track (no other locos on the layout) when setting and checking CV4. 

I have two throttles, a PowerCab and a ProCab.  I unplugged the ProCab and got the same result.

Tried leaving CV4 at zero, setting momentum and checking.  No change, CV4 is still 0.

Not that it should make a difference but PowerCab version is 1.65, CV29 is 38 so no speed table, and decoder is a DZ126.

Clueless.

I suspect that your test was not done properly.  All the decoders I have worked  with (on the last 20 years), both Amercan and European, have the CV3 and 4 functionality ,  and can be written to using POM.   I also doubt that my 1.65B firmware behaves any differently as this MOMENTUM button has been on NCE throttles since the beginning.  My decoder's CV29 is also 38. Besides, momentum should still work as described in the NCE manual, even if speed tables are in use.  Those just control the voltage to the motor, not the timing.

The other answer could be that the throttle unit is defective, but if you press the MOMENTUM button and it lets you enter a value then it seems to be working.  Are you trying this on a single loco or on a consist?  Try on single loco (not consisting).  You might have consist momentum disabled (as the manual warns).

If you start with no momentum (the decoder responds instantly to speed step commands (best observed in 28 speed step mode), if you then set momentum to 5, you should instantly see the lag of the loco vs. the speed step setting on the throttle.  If that is how it behaves, assuming this is the only loco on the track, on your Power Cab press PROG/ESC then 4 to get into programming track mode, then go to CV access and read CV 3 and 4.  You should see 40 and 30 respectively.

[NtheBasement]

OK, mystery solved!  Pilot error on my part.

Wondered if maybe I had a short somewhere.  Didn't seem likely as everything runs fine, but still...  To check that I switched the other blocks (21 blocks from DC days) to the other powerpack (which isn't connected) and sure enough, CV4 read as 40!  So I switched blocks back to the PowerCab and found one block that caused CV4 to read 0.  Tested the rails and they had non-infinite ohms!  Rats, some kind of short.  Then it hit me - the block has a tunnel.  Sure enough there was a loco in there.  Don't remember what I was doing to have left a loco parked in a tunnel but it was a dumb move.

So what was going on was the cab could set the CVs OK, but it would not read them.  Real clue was the read value of zero returned instantly.  When I removed the other loco (or switched out the culprit block) the read took a few seconds to return 40.

[peteski]

So your NCE system  works as expected.   Good troubleshooting!

[Mike C]

Odd... exactly the opposite of what I observed!  Need one of those packet sniffers.  I've also wondered what emergency stop does if the decoder has momentum set.

  Even with momentum E Stop is instant .      Mike

[Cajonpassfan]

Yes. Except for some of my BLI decoders, which ignore it.
Talk about thread drift
Otto K.

[NtheBasement]

Question is how emergency stop is implemented.  Fortunately there is a special speed command; you don't have to zero the decel momentum CV, then send the zero speed packet, then restore the CV back to its original value.

[peteski]

Question is how emergency stop is implemented.  Fortunately there is a special speed command; you don't have to zero the decel momentum CV, then send the zero speed packet, then restore the CV back to its original value.

Description of how this works is in https://dccwiki.com/Term:E-Stop

[mmagliaro]

Sooo... in my DC hand-held... "emergency stop" is "turn the speed knob down really fast".   LOL

[peteski]

Sooo... in my DC hand-held... "emergency stop" is "turn the speed knob down really fast".   LOL

Well, not if you incorporate that delay you've been asking opinions about.