DCC turnouts switch randomly at startup

[TrainArts]

Standard disclaimer, I searched a year back for a previous answer to this issue and didn't find one. If I missed it please feel free to point me at the proper thread...

My DCC layout has five turnouts. #1 is a number 6 crossover, #2-5 are standard number 4 turnouts. I have the basic EZ-command controller. For what it's worth, I have four locomotives, a rail truck, and three lighted passenger cars. Amazingly I can run all these at once, but that's a different story.

QUESTION: When I plug in my controller, at startup, some of the DCC turnouts will switch. This is random, I hear it happen and have to inspect the track to see what was changed. It happens to different turnouts at different times, and has occurred with from one to three random turnouts. It happens every time I plug in the controller.

I can live with this, but has anyone else seen this? Is there a firmware upgrade? Where's the Ethernet port on my controller? (Just kidding on those last two)

Thanks,

Jim

[ABC]

Correct me if I'm wrong, but I didn't think the standard E-Z Command was capable of switching DCC turnouts in the same fashion the Dynamis can switch DCC turnouts. Might I ask how your turnouts are powered?

[TrainArts]

Yeah, the basic EZ-Command controller does this. You press button 9, then Function, and then each button switches it's corresponding turnout.

[Robertj668]

Jim

I have had this problem before and I cannot remember why it happened and why is st oped.  I am off tomorrow and will try to duplicate the problem.

Robert

[Joe Satnik]

Dear All,

This is a classic Power-On-Reset problem for digital logic. 

Say you have a digital logic "memory bit" or "register".  When the circuitry is fully powered up, it can be reliably set to the "state" you want, either 1 or 0, (a.k.a. on or off, high or low).  Example state voltages:  high = 5 volts, low = 0 volts.

Problem is, during power up, crazy things are going on with voltages and you have no idea what state the register will finish the power up cycle in, holding that state until deliberately set to the other state.

If it were designed correctly, the decoder's drivers sending the pulse to the turnout motor coils would be in a "high impedance" (no connection) state until a certain time after the circuitry was powered up and stable, when voltages and states will have settled down.   This "third state" (not driven high, not driven low, but disconnected) would not allow turnout route changes on power up.

Question is, what route do you want on power up?  Main, divergent, or what it was previous? Another option:  jumper wire settable to one of those three?

Hope this isn't too confusing...

Sincerely,

Joe Satnik

   

[TrainArts]

Thanks that makes perfect sense based on my limited study of digital circuits about twenty years ago. Great explanation.

I don't get what you mean by jumpers? I would prefer to have the turnouts keep their previous setting.

It's not a big deal, just something I always wondered about. I realized there's a lot of knowledge here on this board and thought I'd throw it out.

I wonder if the number of locomotives and lighted cars has anything to do with it?

Thanks again.

[Joe Satnik]

Dear TrainArts,

They're kind of like the Master/Slave jumpers on the back of PC hard drives, which are cheaper than electrical switches...

You have answered the question, then:  "Leave turnout route as it was"....

No need for jumpers (or electrical switches) to allow the other 2 options.

Good job.

Sincerely,

Joe Satnik