Watchdog

No.  G

Is there a way to modify a ps2/3 unit to only be in command mode?

No, because no modification is necessary. As long as a DCS engine sees the watchdog signal it will come up in command mode.

getting all units to start in command mode at the same time is only by luck.   1 out of ten always seems not to pay attention.

That's most likely because you're because you're exceeding the amp draw on a single TIU channel.

The "safe" limit for all DCS engines to always come up in command mode is not to give power to more that 6 engines on a single TIU channel. This will vary a bit depending upon what else on the channel is drawing power, e.g., several lighted passenger cars and cabooses.

This and a whole lot more is all in MTH’s “The DCS Companion 3rd Edition", available for purchase  from many fine OGR advertisers and forum sponsors, or as an eBook or a printed book at MTH's web store!

Thanks G.  I figured as much....It would be so nice to be able to power dwn/up sections of the layout w/o screwing around.

One of these days a universal system will be available that controls the layout  (MTH/Lionel others and acc    w/o sending the signal thru my  dirty/poorly connected  tracks. 

Barry.. I was not aware of the six unit restriction... sometimes I can get 10 units to start in command mode other times not. 

 I'm powering the layout from a commercial transformer that will handle >30 amps (fused at 20)  and supplying power to the TIU  Fixed 1 OUT (passive).....  Normal start up steady state is 12-14 amps. ( don't know what start peak is) 

  Is the six engine restriction in play?  and how can I get around it?

Al,

Is the six engine restriction in play?  and how can I get around it?

First, is the power supply that you're using regulated? If not, I'd have a concern since I dot believe that the TIU's TVS's would be active in Passive Mode.

As far as how many engines you could have powering up simultaneously under DCS with a 20 amp supply (limited by a fuse) in passive mode, I cannot say since I've never attempted to do what you're doing.

Does anyone know the current drawn by a PS2 or PS3 board starting up and receiving the watchdog?

Depends on what features.  The board only draws about 0.2 amps conventional with headlight and sounds.  The TIU is .3amps.  Add smoke and your at 1.0 amps.  A fully light diesel with smoke might be 1.4 amps.  These are PS-2 3V figures.  A PS-3 can hit about .7amps as the cap charges before dropping back down.

PS-2 5V can be much higher depending on sound file and features lights.   G

GGG, there have been posts saying that if too many locos are being powered up, there will be failures.  Also some posts saying that wifi is failing to read locos if too many are being started.  Seems to me that if one is simply powering up a track, and the watchdog is keeping the loco from starting up, that draw will be minimal---no smoke, no sound, no lights.