Random Dropping of Consists With DT602D Throttles Updated - 2023-12-17

The author belongs to The Hostlers Model Railroad Club of Ogden, Utah whose modular layout is currently set up at a local mall for the month of December. We have a minimum of 9 members running trains on it, 3 at a time, for about 8 hours a day 7 days a week until New Years Eve. Running started the day after Thanksgiving.

Members have complained that they are randomly losing consists in the middle of running causing runaway locomotives. The author has also experienced this and it is happening relatively often.

The only common factor to the problem is that it only happens to users with DT602D throttles. The 400 and 500 series throttles work flawlessly.

There is also a museum layout where this has happened (to the author at least). There's a lot fewer members running trains there and the author hasn’t had the opportunity to talk to many of them.

Frank Fezzie of the groups.io Digitrax forum brought up the following point:

One difference between the DT602D and the DT402D/DT500D is that the DT602D goes all the way to Power Off as it goes through the stages of saving battery power.  When it has powered off the DT602D can no longer send the "ping" message to the command station every 50 seconds or so which tells the command station that the throttle is still out there controlling its assigned engines.  This can result in the command station purging the slots from active status for that throttle.  When the DT602D is started back up it will attempt to reacquire the engine that it was running but the consist may be damaged by the purge process.  The result is that some of the engines that were in the consist are now not in the consist and are running but not controlled by any throttle.  The DT402D and DT500D also can go into power save mode but they do stay powered on and continue to send the "ping" signal so the command station does not purge their slots.

How to prevent this?…disable address purging in the command station.

<Author’s note>
Disable purging of addresses by setting the Command Station’s OpSw14 to “C”losed.

This change was made to the command station and the author will report back with an update of the results after more run time testing.

<Update 2023-12-17>
After a week of testing by several users running multiple consists it appears that preventing address purging at the command station has corrected the consist dropping problems we were experiencing. The tests included manually dropping and re-consisting the same engines in different orders. 
The mention of "stealing" addresses being a possible cause of the problems will be taken care of by holding a mini-clinic on this at our next club meeting.

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