Hmmm ...
Regarding: 10012 being a coil and 4xxxx a register.
Well the coils and registers are completely different things ... They are
accessed via completely different requests.
That might be some sort of convenience convention, but I wouldn't call that a
standard (I've actually never seen it before)
Would you then just subtract 40000 from every register or would you just
configure registers starting with numbers 40000?
What do the others think? The address format does reference registers ...
should we be doing the translation?
I guess that the general use-case would be that someone has a look at his
Modbus config and says that he wants "Register X"
and not "The Register Y references" (which seems to be one less) ... I might
even swing my vote in favor to using register numbers instead of addresses.
But then I ask myself: How can I address register 0 in ModbusPal ... that would
require an address that's impossible to send.
Chris
Am 15.07.20, 11:51 schrieb "Niclas Hedhman" <nic...@hedhman.org>:
Personall, I prefer that Register Numbers are used in APIs and that the
address is only seen if you analyze the over-the-wire format, but maybe
that is just me. A big reason for this is that any interface presented to
an operator would need to use RegNumbers, as most (possibly all)
documentation of equipment has RegNumbers and some are lacking the
addresses. It is also common that the register type is part of the Register
Number, such as 10012, where the first 1 indicates "coil" (IIRC). and
holding registers are in 4xxxx. Ideally(!), this is also handled by the
register/address parser.
Niclas
On Wed, Jul 15, 2020 at 5:43 PM Christofer Dutz <christofer.d...@c-ware.de>
wrote:
> Hmm .. so are we doing it correctly?
>
> I mean Wireshark isn't the ideal reference here as I have several valid
> packets in the KNX space, where WireShark just says "corrupt package".
>
> So if you enter an "holding-register:42" address it tries to read the
> register number 43 in ModbusPAL.
>
> I guess as we are reading an "address" we are correct and probably as
> ModusPAL says register number, that might be correct too?
>
> Chris
>
>
> Am 15.07.20, 10:54 schrieb "Niclas Hedhman" <nic...@hedhman.org>:
>
> The issue with 1-offset is that the "Register Number" found in
> documentation is at an "Address" one position less. So Reg 41 has
> Address
> 40. Som libraries expect Register Numbers and some expect Register
> Address.
> And every so often, one mixes that up.
>
> On Wed, Jul 15, 2020 at 2:53 PM Christofer Dutz <
> christofer.d...@c-ware.de>
> wrote:
>
> > ....
> >
> > While looking for more Infos I found out I once wrote a tutorial
> page for
> > PLC4X __
> >
> > https://plc4x.apache.org/users/plc4j/virtual-modbus.html
> >
> > I so totally hate searching the web and getting my answers answered
> by
> > myself.
> >
> > Chris
> >
> > Am 15.07.20, 08:31 schrieb "Christofer Dutz" <
> christofer.d...@c-ware.de>:
> >
> > Hi Niclas,
> >
> > when preparing a workshop for the Building IoT we were looking
> for
> > something where you could simulate a Modbus Slave.
> > Most of these were Windows only solutions, so ModbusPAL was one
> of the
> > very few solutions that were pure-java.
> >
> > Don't quite understand what the thing with the offset is however
> ...
> > should be easy to fix ... I mean if I say address 42 in PLC4X,
> Wireshark
> > says 42, but in Modbus Pal I think it has to be 43 ... don't quite
> get it.
> >
> > Chris
> >
> >
> >
> > Am 15.07.20, 03:54 schrieb "Niclas Hedhman" <nic...@hedhman.org
> >:
> >
> > What is ModbusPAL?
> >
> > The 1-offset in Modbus has caused a lot of confusion over
the
> > years.
> >
> > On Tue, Jul 14, 2020 at 11:03 PM Christofer Dutz <
> > christofer.d...@c-ware.de>
> > wrote:
> >
> > > Sorry for the noise ...
> > >
> > > this was a false positive ... the driver was doing things
> > correctly.
> > > It seems the ModbusPAL was just off by one ;-)
> > >
> > > Chris
> > >
> > >
> > >
> > > Am 14.07.20, 15:51 schrieb "Christofer Dutz (Jira)" <
> > j...@apache.org>:
> > >
> > > Christofer Dutz created PLC4X-214:
> > > -------------------------------------
> > >
> > > Summary: [Modbus] Holding register
> addresses
> > have an
> > > offset of 1 (Not reading the correct address)
> > > Key: PLC4X-214
> > > URL:
> > https://issues.apache.org/jira/browse/PLC4X-214
> > > Project: Apache PLC4X
> > > Issue Type: Bug
> > > Components: Driver-Modbus
> > > Affects Versions: 0.7.0
> > > Reporter: Christofer Dutz
> > > Assignee: Christofer Dutz
> > > Fix For: 0.8.0
> > >
> > >
> > > If I set holding the following holding registers to:
> > >
> > > 1000: 41
> > > 1001: 42
> > > 1002: 43
> > >
> > > And then read: holding-register:1001 ... I get the
> value 43
> > returned.
> > >
> > >
> > >
> > > --
> > > This message was sent by Atlassian Jira
> > > (v8.3.4#803005)
> > >
> > >
> >
> >
> >
>
>
