I fail to see why a sound decoder can work in direct byte mode and
not in direct bit mode or paged mode. The speaker load excuse sounds
like a smokescreen to me to cover up for simple bad design. In all
cases the requirement is for a 60mA current pulse of 5ms.

It costs a few cents to add a transistor and a load to generate the
correct ACK pulse during programming.

There is NO excuse for any decoder to not support readback in all
modes.

This is not a problem with the NMRA RPs, it is purely a design
decision by the manufacturers to not fully implement the RP.

Regards,

Andrew

--- In sprog-dcc@..., "J. Michael Hewitt"
<jmhewitt@...> wrote:
>
> I can write and read to Soundtraxx decoders with the SPROG without
> problem.
>
> I have a decoder I am using for sound only, but don't know if it is
> Sound only or that I don't have a motor connected.
>
> I will check and reply.
>
> note that the SPROG ONLY has a Service mode. however, it can run a
train!!!
>
> Michael
>
> Jon Miller wrote:
> >
> > Another look at this problem is that it was explained to me that
with a
> > speaker load (sound only decoders) the loading was too slow for a
> > Direct Bit
> > response thus Direct Byte was used. While a little faster Direct
Byte is
> > not much different from Paged Mode.
> >
> > In Blueline's defense I checked the Soundtraxx DSX (a sound only
> > decoder) and see it doesn't use Direct Mode only Paged Mode.
> > Digitrax sound decoder says Direct Mode but I'm not sure if you
could
> > read/write in Service Mode with only the sound decoder connected.
They
> > basically say if it doesn't work in Service Mode (programming
track) then
> > use Ops Mode (main line).
> > It appears that a manufactures out for not being able to use
Service
> > Mode is simple to says if it doesn't work use Ops Mode. You can't
read in
> > Ops Mode which is why I never use it.
> >
> > So here is the catch 22. NMRA says;
> > sic---are submitted for Conformance after 1-Aug-2002, must
support Direct
> > Mode."
> > Sound only decoders don't like Direct Bit Mode so we have a
problem (or
> > at least it appears so) and it's not really the manufactures,
it's an
> > NMRA
> > problem. They never thought the market would have sound only
decoders I
> > guess!
> >
> > Jon Miller
> > AT&SF
> > For me time has stopped in 1941
> > Digitrax, Chief/Zephyr systems, JMRI user
> > NMRA Life member #2623
> > Member SFRH&MS
> >
> >
>