Hi Niclas,

Protocol-wise the numbers could be up to 65535 as they use an unsigned 16 bit 
integer as an address.

I guess what would be interesting, would be what address is going over the wire 
for "30001" for example.
Also as a register is always a 16 bit value, the increments by two sort of 
puzzle me.

I think Modbus is an extremely simple protocol but we need to get a feeling for 
it's usages.

It does seem as if the industry tends to wrap some aspects in software 
bubble-wrap ... we gotta find out what's below.

Chris


´╗┐Am 15.07.20, 15:23 schrieb "Niclas Hedhman" <nic...@hedhman.org>:

    It is a common format in equipment documentation. I am currently working
    with an electric meter. See screenshot from its manual;
    https://ipfs.subutai.io/ipfs/QmPsra6ExrkSX9GCYWgHa6CTfJbBnddLVXJ3NmJjmAYrAk

    At protocol level, there are no such "high numbers", just that the industry
    got used to write "4" instead "holding register". It is a "people thing",
    not a technical one.

    HTH
    Niclas

    On Wed, Jul 15, 2020 at 6:11 PM Christofer Dutz <christofer.d...@c-ware.de>
    wrote:

    > 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)
    >     >     >         >
    >     >     >         >
    >     >     >
    >     >     >
    >     >     >
    >     >
    >     >
    >
    >

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