The cab has a "yard mode" where just the knob controls speed AND direction - in the middle is stop, turn one way and speed increases forward, turn the other way and the speed increases in reverse. This is so you cna switch cars back and forth in the yard with just your hand on the throttle knob, no pushing the direction button.
Some decoders have a "switching speed", function will vary depending on the decoder, but on most it chops the top speed in half and cuts acel and decel momentum in half so you get quicker response and better slow speed control. Not all decoders support it. Those non-US brands that translate to the Queen's English may term it "shunting speed" in the documentation.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
I don't know what "yard speed" is. There is an option for what they call "yard mode", but that has to do with where zero speed is. In normal operation, when you turn the encoder all the way down the loco will stop. In yard mode if you turn the encoder wheel to slow the loco the loco will stop, but will then start to increase speed in the opposite direction. See page 20, item 5 at the following link: http://www.ncedcc.com/images/stories/manuals/power_cab_manual_v1.28.pdf.
Note that it says that this only works when the handset is used as a Procab. I'm not certain, but I believe that this means if you are using the handset as a PowerCab you can't use the yard mode feature.
Now, if it is your desire to have a specific loco set up as the yard switcher and have the top speed on that loco limited to a lower value, say 15 mph, then that is accomplished but setting the Vmax CV in the loco in question.
I have a NCE power pack starter set but in the manual deliverd in he box there is nothing hw you can set it to yard speed.
Which Function button must be activated for this?