With DCC, you have Function Control
of the loco's lights and other electrical devices on board. Each decoder
responds to Function Controls sent to its two- or four-digit address,
whichever the decoder is programmed to respond to. When a loco is
MU-consisted to another address, then it gets it's motor control from
the consist address, but it's Function Control is still from the decoders
original two- or four-digit address.
There is a feature called Decoder-Assisted
Consisting (DAC). This is one of four ways to MU consist two or
more locos together to operate as one unit. There is another feature
called DAC Function Control. It is used to transfer Function Controls
from the loco address to the Decoder Assisted Consisted address. Refer
to Decoder-Assisted Consisting
for more information about DAC and MU consisting.
When building an MU consist, a consist
address is chosen - an address used to send control packets to the
entire consist. Most people use the base address of the lead loco
for the consist address. But some people use a phantom consist address
(an address that is not used by any loco on the layout) to consist
all locos to. In this case, the phantom is the lead loco and all real
locos in the consist are consisted to that phantom.
Any loco that is consisted to the
consist address will NOT have Function Control of the lights or anything
else on the loco from that consist address. The only thing that will
respond from that consist address is the motor's speed and direction
commands. You have to select that loco's base address to operate its
functions independently of the consist's speed and direction. This
is one situation where Digitrax's dual -knob throttles come in handy.
While controlling the consist speed, direction, and lead loco's functions
with the right knob, you can select consisted loco addresses into
the left knob to control the lights and other functions there.
For example, let's say that you're
building a consist with the lead loco's address of 25 and you are
going to consist loco #10 to it. When the consist is complete, both
locos in the consist will operate speed and direction from the consist
address of 25. However, when you turn the lights on or off (or any
other function, for that matter), only the lights on the loco with
the base address of 25 will respond. To operate the lights on loco
#10, you will have to select address 10 to control those functions.
People using Digitrax's two-knob throttle usually leave consist control
in the right knob and select the consisted loco into the left knob
for Function Control. Even though you will have loco #10 selected
into the left knob for Function Control, you will not be able to control
it's speed or direction there. Speed and direction of all locos in
the consists is controlled only from the consist address.
However, there could be a situation
where you might want to have consisted locos' functional control to
respond from the consist address. This is where DAC Function Control
comes in.
With DAC Function Control, you can
program each decoder to provide DAC Function Control for any function
the decoder has. Each function is handled separately. This allows
you to provide Function Control of one function and not another, if
desired. For example, you probably wouldn't want the headlight of
the second loco to go on and off with the lead loco's, but you may
want its horn and bell to operate even though it's not the lead loco.
In this case, you would program the headlight to not have control,
but functions 1 and 2 (bell and horn) to have Function Control with
the DAC consist address. In this situation, the headlight can still
be controlled from that decoder's base address while the bell and
horn are controlled from either consist or base address.
DAC Function Control does not affect
the functional control when it is not consisted, but only when it
is consisted via Decoder-Assisted Consisting. The decoder knows when
to provide control and when not to, based upon whether or not there's
an address in CV19.
When the loco is not consisted, there
is no address in the DAC address CV (CV19). As such, the loco gets
its motor and Function Control from the base address. If there is
an address in the DAC CV, then the loco gets its motor control from
the DAC address and checks the DAC Function Control CVs to see which
Function Control to get commands from the DAC address. This sounds
cumbersome in the description, but all these decisions are made by
the decoder in millionths of a second.
Note that DAC Function Control only
works when consisting via Decoder-Assisted Consisting. It does not
work with Command Station Consisting. |
