A slot is a memory location in the command station that holds an active decoder address. The number of slots is the number of locomotives that the command station can support in operation at a time.
When the available slots are filled with decoder addresses, trying to select another locomotive address to run generates the "slot=max" error code. When all the slots are full you can't select another address until one is released from the system. See Clearing your Command Station's Mobile Decoder Slots below for how to prevent this from happening.
The DCS100 Command Station/Booster that is included with Super Chief Xtra and other Chief starter sets comes from the factory set for 22 available "slots". This can be increased to 120 slots.
The DCS100 Command Station/Booster has an internal routine that periodically purges the slots of locomotives which are not currently being used. This happens only when loco addresses are set to 0 speed. This means it is a good idea to make sure when your loco is stopped that it is set to 0 speed and not a very low speed.
To increase the DCS100's slot refresh capacity to 120, change the DCS100 OPSW#44 to "c".
General Instructions for Closing Command Station Option Switches (for specific instructions for your command station and throttle, see the instruction manual for your equipment:
1. On the command station, set the MODE toggle switch to the OP (center) position.
2. Using your throttle go into Switch Mode
3. Enter the Option Switch number you wish to change (in this case 44)
4. Press the "c" key on the throttle.
5. You will hear a beep.
6. On the command station move the MODE toggle down to SLEEP then back up to RUN.
7. Using your throttle, turn Track Status back on.
Clearing your Command Station's Mobile Decoder Slots
Most command station problems are caused by filling up the command station's available slots by the following:
1. Operators failing to zero the speed of unused addresses
2. Operators failing to release unused locos from their throttles.
Once the slots available are full, additional loco addresses can't be selected. Opeartors will get the "FF" or "Slot Max" message on their throttles. Phantom addresses can be removed by closing the appropriate option switch in the booster.
Closing OpSw#36 will clear all the loco addresses from the slots available in your command station.
Many layout owners set OpSw#36 to closed after each operating session to make sure the slots available in their command station are free for the next session to prevent having to do this during the next session.