DT402D, DT500D and UT4D Not Working Properly With The UR93

Frank Fezzie gathered a lot of information from users on the Digitrax groups.io forum that were having communication problems with the UR93 and older Digitrax throttles (DT402D, DT500D and the UT4D). Frank has been a major player in solving some pretty tough problems with Digitrax issues in the past.

Here is his final report on the resolution of this problem.
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Digitrax appears to have had a small batch of recent RF28 modules that had slightly fast timing causing them to fail to work properly with older throttles such as the UT4D, DT402D, and DT500D.  Digitrax has to deal with these on a case by case basis.  The affected units may have to go back to Digitrax for adjustment.  It is important to note that not all UR93's have this issue.

The latest UR93 IPL, 30Aug21, does modify a number of units into a timing range closer to legacy Duplex units, allowing those UR93’s to work well with the older throttles.

Most customers will not have an issue, particularly on older UR93's and if they are running an "all-modern" duplex setup.  The DT602D and UT6D's throttles work well with all UR93’s and UR92’s.

If you have trouble with older throttles such as the UT4D, DT402D, and DT500D failing to work wirelessly with your UR93 then do the following.

1. If possible test your older throttle with a UR92 to confirm that the throttle works properly in wireless mode. 
2. Install the 30Aug21 IPL update into your UR93. 
3. If you still have problems contact the Digitrax Help desk for further assistance. Your UR93 may have to go back to Digtrax for adjustment.

After our two UR93's were adjusted by Digitrax my testing of the units went very well.  I have seen no need to close option switches 11 and 12 (or was it 12 and 13) to prevent the UR93 from changing channels.  When changing duplex group information on the UR93’s remember to use a Digitrax throttle.  JMRI appears to not always set the information in the UR93 correctly.  I suspect DigiGroupSetup would also work but I did not test it.

I saw significant improvement in range of the UR93.  On our museum layout we use one UR92 to cover layout in a big room.  Coverage was marginal at the corners of the room or if I used my body to shield the DT402D throttle.  After replacing the UR92 with the UR93 I found that coverage was solid all throughout the room and I could not trigger the flashing white light on the throttle even when shielding it with my body while in the far corners of the room.

I tested with a UR93 and a UR92 on the same loconet separated by about 50 feet.  All throttles worked well with both radios and switched between the units properly.  They did favor the UR93 due to its greater signal strength and I had to get within 10 feet of the UR92 before they would switch to it.  I would expect that large "basement empire" layouts may find that a single UR93 will cover the bulk of the room and one or more UR92's could fill in where there is a dead spot, in a separate room for example.  My general advice would be to start by locating one or more UR93's to provide good overall coverage and then use UR92's if desired to fill in the areas with weak signal.  Use as few UR devices as possible to minimize the amount of switching between radios that a throttle has to do.

One problem that still exists is that the throttles will sometimes miss a message coming from the system to the throttle.  There is no error checking or missed message checking for signals from the UR93 or UR92 to the throttle.  This is part of the design of Digitrax Duplex.  This error is most commonly seen when doing one of the following;

1. Acquiring an engine, a digit entered will not show up, or hitting ENTER to acquire appears to fail leaving the engine # flashing.
2. Entering a turnout number in switch mode, a digit is entered and fails to show on the screen.
3. Changing direction or turning a function on or off.  Pressing the button fails to activate the change or the change does not show on the screen.

I saw less of these problems with the UR93 but I still saw some.

My final conclusion is that the UR93 works well with all duplex throttles and works well with UR92's.  If you have problems, make sure that all devices have the latest IPL software installed.  If you still have problems then contact Digitrax for assistance.  You may have units with RF28 radio modules that are out of tolerance.

Frank Fezzie

<Addendum>

There have been a few reports about UT6D and DT602D throttles, with the RF28 module, failing to work with UR92’s.  This may be a similar problem where in this case the RF28 module in the throttle fails to talk to the RF24  module in the UR92.  I gave Digitrax Engineering a heads up message about it but I have not heard anything back.  As with the UR93 problem, I suspect that they have to handle these on a case by case basis with the defective equipment going back to Digitrax for adjustment.
 
Relatively few people have complained about having either issue so I also suspect that Digitrax is correct when they say that most equipment will not have these problems.
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Thanks Frank, this will help out a lot of people and will probably get things back on track with Digitrax.

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