DCC Impulses Column - 3
Enter the all-purpose CV number 29. Bit 5 of CV 29 tells the
decoder whether it is to respond to the short or long address.
If bit 5 = 0, the decoder listens to the short address. If the
decoder is to respond to the long address, bit 5 needs to be 1,
raising the number in CV 29 by a value of 32. Thus, if you read
CV 29 and get a value of 32 or more – frequently 33 to 39 – the
decoder is responding to a long address. If it is less than 32 you
know that it is responding to the short address.
There is a fine online calculator available to determine the val-
ues to put in to CVs 17 & 18, if you want to do it yourself. It also
calculates CV 29, for those so inclined. Check it out as this web
link:
. Thanks to
the 2 MM Scale Association in the UK for permission to recom-
mend their site. You may use DecoderPro similarly: go to the
basic panel and make your selections, and go to the CV panel
and see what the resulting values are.
The consist address (CV 19) is a bit less confusing. If CV 19 = 0,
there is no consist address stored and the loco will respond to
either the short or long addresses as dictated by CV 29, above. If
CV 19 is anything other than zero, that will override whatever CV
29 dictates and become the operational name. So, now we have
the option of “Tommy,” in addition to “Tom” and “Thomas.”
Allowed consist addresses are 1 to 127. If the loco is to run in
reverse when it is in a consist (think of locos running back to
back), then 128 gets added to the consist address, making allow-
able values for CV 19 to be 1 to 255, when the loco is in a con-
sist, or zero when it is not in a (decoder based) consist.
3: Two diesel locos making up a consist – this is train 103
from the PCMRC layout after it has run around its train and
is ready to run back home. Loco 2016 has a value of 103 in
CV 19; the 2035 has 231 (103 + 128) in CV 19. See figure 7.
3
MRH-Feb 2014
