Page 34 Non-Sound Decoder MX618 - MX634 and Sound Decoder MX640 - MX648
4
Feedback -
“Bidirectional communication”
All ZIMO decoder types have been equipped with a type of feedback ever since DCC was formed,
which has always been a major difference to competitors’ products:
- the
ZIMO loco number identification
is part of ZIMO DCC decoders since 1997 and as
far back as 1990 with ZIMO’s own data format (which is no longer in use today). It can only be used
with ZIMO DCC systems (MX1…MX10, MX31ZL, MX32ZL…) and together with ZIMO track section
modules (MX9 and successors): After receiving DCC packets, the decoder sends acknowledgment
pulses which will be utilized to identify and locate the decoder in the respective section of track.
- all ZIMO decoders are ready for the
“bidirectional communication”
ac-
cording to
“RailCom”
since 2004; it is operational in newer decoders
such as the MX630 and MX640 series from the beginning (basic functions,
ongoing expansion with future software updates).
“Bidirectional” means that the information transfer within the DCC protocol is not only flowing towards the decoder
but also in the opposite direction; that is, not just driving, function and switch commands are being sent to decod-
ers but also messages such as acknowledgements, actual speed as well as other status information and CV read-
outs are being received from decoders.
The functioning principle of RailCom is based on the introduction of short cut-outs (max. 500 micro seconds) by
the command station to the otherwise continuously sent DCC signal. These cut-outs provide the time and oppor-
tunity for the decoders to send a few bytes of data to locally mounted detectors.
Relevant CV’s for RailCom configuration:
CV
Designation
Range
Default Description
#28
RailCom Configuration
0 - 3
3
Bit 0 - RailCom Channel 1 (Broadcast)
0 = OFF
1 = ON
Bit 1 - RailCom Channel 2 (Data)
0 = OFF
1 = ON
#29
Basic configurations
0 - 63
14 =
0000
1
110
Which is
Bit 3 = 1
(“RailCom“
turned on)
Bit 0 - Train direction:
0 = normal, 1 = reversed
Bit 1 - Number of speed steps:
0 = 14, 1 = 28
Bit 2 - DC operation (analog):
0 = off 1 = on
Bit 3 -
RailCom (“bidirectional communication“)
0 = deactivated
1 = activated
Bit 4 - Individual speed table:
0 = off, CV # 2, 5, 6, are active.
1 = on, according to CV ‘s # 67 – 94
Bit 5 - Decoder address:
0 = primary address as per CV #1
1 = ext. address as per CV #17+18
#136
Speed feedback correc-
tion
or km/h
– control num-
ber during calibration
run
RailCom
display
factor
128
RailCom speed feedback correction factor.
or (see chapter 5.8)
reading out the result of the internally computed speed
after the calibration run.
CV
Designation
Range
Default Description
#158
Several special bits +
RailCom variants
0 - 127
4
ATTENTION: all other bits in this CV are used for a va-
riety of different special sound settings.
Bit 2 = 0: RailCom speed (kph)
– feedback using the
“old” method (for MX31ZL ! Id 4)
= 1: RailCom speed (kph)
– feedback using the
new STANDARDIZED method (Id 7).
With the help of
bidirectional communication
according to RailCom
decoders will acknowledge received commands -
- which increases operational reliability and the bandwidth of DCC systems because already
acknowledged commands don’t need to be sent repeatedly;
current decoder data
is sent to the command station (“global detector”) -
-
e.g. “real” (measured) train speed, motor load, routing and position codes, “fuel reserves”, current
CV values on demand from decoders is sent to the command station or more precisely, to a
global
detector
in the command station;
decoder addresses are recognized by “local” detectors -
- the actual loco positions are determined by local detectors connected to individual track sections (in-
tegrated in future MX9 track section modules), which has been possible with ZIMO’s own loco num-
ber recognition for a long time, even without bidirectional communication.
RailCom will be further developed over the coming years and new applications added which of course
requires new software updates in decoders and other equipment. ZIMO decoders as of 2009 are able
to send their own loco address from an isolated section of track (with a so called broadcast method,
very fast, although only for one loco inside that section), send CV content on demand along with
some decoder data such as actual speed in kph, load and decoder temperature.
On the system side, only one third party product has been available from the beginning
– the address
display LRC120, which is a “local” RailCom detector displaying the loco address of one track section.
In 2007, the ZIMO MX31ZL came to market as the first command station with an integrated “global”
RailCom detector.
In the first quarter of 2013, ZIMO will deliver the new MX10 command stations with integrated detec-
tors for RailCom. The MX32 cab (released early in 2011) uses feedback functions from the start
(speed indicator, CV-reading), but until the appearance of the MX10 is accessible only in connection
with the MX31ZL.
RailCom is activated in ZIMO Decoders with
CV #29, Bit 3 = 1
AND
CV #28 = 3
These are usually default settings on a new decoder, but RailCom is turned off by default in many
sound projects or OEM CV sets and
must therefore be activated first with above CV’s (see table
above).
ATTENTION (if speed-feedback does not work): see CV #158, Bit 2 (in table above).
“RailCom“ is a registered trademark of Lenz Elektronik GmbH.
