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Disabling DCC Specialties Hares & Wabbits with Push Button Lockout

Posted by on Mar 14, 2017 in Tony's Tips |

On a couple of our club modules we have elaborate control panels and use DCC Specialties Hare accessory decoders with push buttons used to manually select turnout routes (red/black buttons). Unwary fingers are a problem at some shows, resulting in derails, electrical shorts, and even a melted truck or two.

Could a master SPST push-button be put in the black ground wire and all the Wabbit’s run through it? And would it be OK if that one push button went to a single ground instead of back to their originating boards?

Any and all input is appreciated…..Peter

DCC Specialties Hare

If you are using Hares and/or Wabbits, they have a feature to solve this problem without any wiring changes. It is called Push Button Lockout (PBL). It is designed for clubs with exactly the problem you are trying to cope with. By default, this feature is disabled. Basically, once it is enabled on all of your Hares/Wabbits, a single Accessory (SWCH) ON command to your selected accessory address will disable ALL push buttons on the layout. Conversely, a single command to the selected Accessory (SWCH) address will re-enable ALL push button inputs on the layout.

How to Use Push Button Lockout

  1. Select an Accessory Address that will be used by all Hares on your layout to enable or disable Push Button Lockout (PBL).
  2. Program CV88 to 173 and then send an Accessory Command (or SWCH) to your selected lockout address (e.g. 500).
  3. The command can be either ON or OFF. This enables the PBL logic, and will allow you to enable or disable manual inputs by sending Accessory Commands to your selected lockout address.
  4. If you have already set an Accessory Address for the PBL logic, you can enable or disable the PBL function by setting CV88=1 (enable) or CV88=0 (disable).
  5. When PBL is enabled, if you send an ON (1,c) Accessory Command to your selected lockout address (here 500), all of the PBL enabled Hares will not respond to any push button commands.
  6. If you send an OFF (2,t) Accessory Command to your selected lockout address, all enabled Hares will now respond to all push button commands.
  7. Once this feature is enabled, you can use it, for example, at a train show to disable ALL of your manual inputs to prevent visitors from “helping” you dispatch trains.  Should you need to use a manual input, a single DCC command will enable the inputs, allowing a quick point change, and then a single DCC command will again disable all of the manual inputs.

The Wabbit has the same feature except that you set the PBL address by setting CV72=173 instead of using CV88. With the Wabbit, you also need to set SWA and SWB CVs separately.

The Jack Wabbit has the same feature, and it is accessed the same way as the Wabbit:

  1. Write 173 to CV72
  2. Send an address to enable PBL.
  3. After sending the address, PBL is automatically set to OFF, but an ON Accessory Command to the address programmed will turn ON PBL (i.e. the push buttons will not work).
  4. As with the Wabbit, SWA, SWB, SWC, and SWD must be programmed separately, but multiple SWAs, SWBs, etc. can be programmed at once.

You can place more than one Hare into program mode and issue the CV88=173 command and then the address. This will enable PBL on multiple units at the same time. You can also do all Wabbit SWA at once and then all Wabbit SWB at once. The Wabbit takes about 4 seconds after you initiate the PBL enable/disable before the inputs are actually inhibited.