Re: [foxboro] FBM230/Modbus slave too fast problem [end of the story]
- From: Pablo Lioi <plioi@xxxxxxxxxxx>
- To: "foxboro@xxxxxxxxxxxxx" <foxboro@xxxxxxxxxxxxx>
- Date: Mon, 16 Mar 2015 15:19:24 +0000
I just discovered I made a sad mistake while investigating this problem.
I concentrated on the timing issue as described before, mainly because I had
already experienced that problem, but also because you really never know what
the master is exactly doing in the case of the FBM230, at least with an old
version of the driver, as in my case.
It was not until today, when I got hold of yet another Modbus RTU/Modbus TCP
gateway, one that lets me delay the response on the RS-232 side, that I had a
real opportunity of testing my asumptions. So it came as a big surprise when I
connected the new equipment and found that communication didn't work, either. I
went back to the protocol analyser and confirmed that my 50 ms delay was
working all right. Clearly, I had to look elsewhere.
As I stated before, I was already reading a value from the ROC with Modbus RTU
over RS232. The register I'm reading is 47017. Whether I configure it as 47017
or as 47017:F4, the FBM230 issues a command FC=3, Starting Register: 7016,
Number of Registers: 2. The ROC returns registers 7016 and 7017 (16-bit each),
as expected by the master and that's the end of it. Enter the gateway. The
query is still the same, but now the response comes from the Ethernet port of
the ROC. On this port, register 7016 is interpreted as 32 bits, so the response
carries 2 32-bit registers, that are interpreted as 4 16-bit registers by the
master, and discarded.
So that's it. It would be nice if I could tell the FBM230 to translate 47017
(with or without ":F4") as a query for only register 7016 and expect a 32 bit
value, but I don't think that's possible. I had a look at B0700BG rev K and for
what I see, you can't do that with the latest revision of the driver either.
Thanks to everybody that helped me with this issue.
Regards
Pablo Lioi
Total Austral S.A.
Tierra del Fuego
Argentina
> From: plioi@xxxxxxxxxxx
> To: foxboro@xxxxxxxxxxxxx
> Subject: Re: [foxboro] FBM230/Modbus slave too fast problem
> Date: Fri, 13 Mar 2015 23:51:00 +0000
>
> I would like to share my conclusions about this problem so far, as I think
> they may be useful for others.
> In my original post I omitted some details for the sake of simplicity, but
> now I will describe my problem and findings more thoroughly.
> Right now I have an FBM230 talking to a Fisher ROC using Modbus RTU over
> RS232, at 9600 bps, on port 3. This communication is working ok.
> I want to modify my system so that I can use Port 3 to communicate with 3
> (networked) Fisher ROCs using Modbus/TCP. So I installed a Modbus Serial to
> Modbus TCP Gateway (Schneider TSX ETG100), connected Port 3 of the FBM230 to
> the serial port of the gateway and the Ethernet Port of the gateway to the
> ROC network. My first test was to read one register from the same ROC I was
> previously reading over RS-232. The ROC replies and the gateway converts the
> response back to Modbus RTU and sends it to the FBM230, but the FBM230
> discards the message and retries.
> I know for sure that settings, cables, dip switches, etc., are Ok, because
> I'm monitoring the line with a protocol analyser. As I stated before, I've
> already had problems with slaves that replied too quickly to polls from the
> FBM230, so this time I made some measurements with the protocol analyser. The
> results are as follows:
> In my original configuration, with the FBM230 reading from the ROC over RS232
> at 9600 bps, the time between the last byte of the query and the first byte
> of the response message is 16 ms.
> In my new configuration, with the FBM230 connected to the gateway al 9600
> bps, the time between the last byte of the query and the first byte of the
> response message is 8 ms. If I change the baudrate to 38400 bps, the time
> goes down to 5 ms.
> Conclusions so far:
> - In my new configuration, the difference in response time between 9600 and
> 38400 bps is due to the 3.5 char times the gateway waits to mark the end of
> the incoming message on the serial port. At 9600 bps, this time is 3.4 ms and
> at 38400, 0.8 ms. As nothing changes on the Ethernet side, I am assuming that
> the time it takes for the gateway to convert the message, send it to the ROC
> over Ethernet and get the response is the same in both cases (4.5 ms, more or
> less).
> - The FBM230 modbus master driver software is doing something (flushing the
> receive buffer, probably) that doesn't allow it to cope with responses that
> arrive in less than, lets say, 10 ms.
> - The only solution I see is to install a gateway with a configurable
> response delay on the RS-232 side, or something to that effect.
> Thanks to everybody
> Regards
> Pablo Lioi
> Total Austral S.A.
> Tierra del Fuego - Argentina
>
> > From: dmarc-noreply@xxxxxxxxxxxxx
> > Subject: Re: [foxboro] FBM230/Modbus slave too fast problem
> > Date: Thu, 12 Mar 2015 12:15:59 -0400
> > To: foxboro@xxxxxxxxxxxxx
> >
> > I believe if you can produce the foxboro PO or sales order they will send
> > you an updated driver at no cost. It will be a computer transfer.
> >
> > Sent from my iPhone
> >
> > > On Mar 12, 2015, at 11:00 AM, Pablo Lioi <plioi@xxxxxxxxxxx> wrote:
> > >
> > > Scott,
> > > As I stated before, my driver is version 1.1 and I am using B0700BG-C.
> > > Supported device counters are Good Messages Sent, Good Messages Received
> > > and Timeouts.
> > > I suppose I should upgrade the driver...
> > > Regards
> > > Pablo Lioi
> > >> From: Scott.Landry@xxxxxxxxxxxxxxxxxxxxxx
> > >> To: foxboro@xxxxxxxxxxxxx
> > >> Date: Thu, 12 Mar 2015 08:51:55 -0400
> > >> Subject: Re: [foxboro] FBM230/Modbus slave too fast problem
> > >>
> > >>
> > >>
> > >> Pablo,
> > >>
> > >>
> > >> Latest Modbus driver is V2.3.4 (B0700BG-J document)
> > >>
> > >> If you are using RS-422 or RS-485;
> > >>
> > >> Set the RS-232 switches for the channel such that the C5 and C6 switches
> > >> are in
> > >> the CLOSED position and the rest of the switches are in the OPEN
> > >> position (see
> > >> Figure 4-15 on page 39).
> > >>
> > >>
> > >>
> > >> Something else I do when I set a FDSI interface up is configure all
> > >> the port and device counters, possible.
> > >> I also have a graphic I re-use so they are easy to see (depends on
> > >> the driver) some drivers
> > >> have a script to build the blocks and graphic(s). Although not
> > >> Modbus driver.
> > >>
> > >>
> > >> Port Counters:
> > >> 1. Number of good messages sent
> > >> 2. Number of good messages received
> > >> 3. Number of parity errors
> > >> 4. Number of framing errors
> > >> 5. Number of checksum errors
> > >> 6. Number of transmit errors
> > >> 7. Port Scan Time
> > >> 8. Reset Counters
> > >>
> > >> Device Counters:
> > >> 1. Number of good messages sent
> > >> 2. Number of good messages received
> > >> 3. Response timeout
> > >> 4. Number of Modbus Device Exception responses
> > >> 5. Number of Modbus gateway exception responses
> > >> 6. Last Error message received from the gateway
> > >> 7. Configured Options
> > >> 8. Number of Over Scans
> > >> 9. Over Scan time high
> > >> 10. Group Scan time
> > >>
> > >>
> > >> Regards,
> > >>
> > >>
> > >> Scott
> > >>
> > >> ________________________________________
> > >> From: foxboro-bounce@xxxxxxxxxxxxx [foxboro-bounce@xxxxxxxxxxxxx] On
> > >> Behalf Of Landry, Scott [Scott.Landry@xxxxxxxxxxxxxxxxxxxxxx]
> > >> Sent: Thursday, March 12, 2015 7:14 AM
> > >> To: foxboro@xxxxxxxxxxxxx
> > >> Subject: Re: [foxboro] FBM230/Modbus slave too fast problem
> > >>
> > >> Pablo,
> > >>
> > >>
> > >> Try playing with the driver scan rate, slower and faster. See what
> > >> difference it makes, if any.
> > >>
> > >> Are you using an xml device config file ?
> > >>
> > >>
> > >> Regards,
> > >>
> > >>
> > >> Scott
> > >>
> > >> ________________________________________
> > >> From: foxboro-bounce@xxxxxxxxxxxxx [foxboro-bounce@xxxxxxxxxxxxx] On
> > >> Behalf Of Pablo Lioi [plioi@xxxxxxxxxxx]
> > >> Sent: Thursday, March 12, 2015 5:10 AM
> > >> To: foxboro@xxxxxxxxxxxxx
> > >> Subject: Re: [foxboro] FBM230/Modbus slave too fast problem
> > >>
> > >> I'm using RTU, but my communication is not a radio link. The FBM230 and
> > >> the slave are inside the same cabinet.
> > >>
> > >>> From: dmarc-noreply@xxxxxxxxxxxxx
> > >>> Subject: Re: [foxboro] FBM230/Modbus slave too fast problem
> > >>> Date: Wed, 11 Mar 2015 15:18:10 -0400
> > >>> To: foxboro@xxxxxxxxxxxxx
> > >>>
> > >>> Are you using Modbus rtu or ASCII? On radio units I have had better
> > >>> luck with Modbus ASCII.
> > >>>
> > >>> Sent from my iPhone
> > >>>
> > >>>> On Mar 11, 2015, at 1:28 PM, Pablo Lioi <plioi@xxxxxxxxxxx> wrote:
> > >>>>
> > >>>> Hi everybody,
> > >>>> I'm sending this again because for some reason carriage returns seem
> > >>>> to have been lost and the post was difficult to read.
> > >>>> In the past I had a serious problem with an FBM230 with Modbus
> > >>>> protocol communicating with a slave using RS-232, in RTU mode.
> > >>>> When the slave response to any query from the master arrived too fast,
> > >>>> the FBM would ignore the response and retry. I finally worked around
> > >>>> the problem delaying the response from the slave a few milliseconds
> > >>>> using a setting (at the slave device) that was meant for radio
> > >>>> communication (RTS to TxD delay).
> > >>>> I am now facing the same problem again, with another slave device. The
> > >>>> problem is that this time I have no way to delay the slave response. I
> > >>>> tried using RTS/CTS handshake on the RS-232 line, but the problem
> > >>>> remains. I know for sure that cable and switch settings at the TA are
> > >>>> ok because I'm looking at the line with a protocol analyser and see
> > >>>> correct query and response messages.I would like to know if somebody
> > >>>> else has experienced this problem too.
> > >>>> Regards
> > >>>> Pablo Lioi
> > >>>> TOTAL AUSTRAL S.A.
> > >>>> Tierra del Fuego - Argentina
> > >>>>
> > >>>>
> > >>>>
> > >>>> _______________________________________________________________________
> > >>>> This mailing list is neither sponsored nor endorsed by Invensys Process
> > >>>> Systems (formerly The Foxboro Company). Use the info you obtain here at
> > >>>> your own risks. Read http://www.thecassandraproject.org/disclaimer.html
> > >>>>
> > >>>> foxboro mailing list: //www.freelists.org/list/foxboro
> > >>>> to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
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> > >>>
> > >>>
> > >>> _______________________________________________________________________
> > >>> This mailing list is neither sponsored nor endorsed by Invensys Process
> > >>> Systems (formerly The Foxboro Company). Use the info you obtain here at
> > >>> your own risks. Read http://www.thecassandraproject.org/disclaimer.html
> > >>>
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> > >>> to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join
> > >>> to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave
> > >>
> > >>
> > >>
> > >> _______________________________________________________________________
> > >> This mailing list is neither sponsored nor endorsed by Invensys Process
> > >> Systems (formerly The Foxboro Company). Use the info you obtain here at
> > >> your own risks. Read http://www.thecassandraproject.org/disclaimer.html
> > >>
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> > >> Systems (formerly The Foxboro Company). Use the info you obtain here at
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> > >> *** Confidentiality Notice: This e-mail, including any associated or
> > >> attached files, is intended solely for the individual or entity to which
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> > >> legally privileged. If you have received it in error, you are on notice
> > >> of its status. Please notify the sender immediately by reply e-mail and
> > >> then delete this message from your system. Please do not copy it or use
> > >> it for any purposes, or disclose its contents to any other person.
> > >>
> > >>
> > >> _______________________________________________________________________
> > >> This mailing list is neither sponsored nor endorsed by Invensys Process
> > >> Systems (formerly The Foxboro Company). Use the info you obtain here at
> > >> your own risks. Read http://www.thecassandraproject.org/disclaimer.html
> > >>
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> > >
> > > _______________________________________________________________________
> > > This mailing list is neither sponsored nor endorsed by Invensys Process
> > > Systems (formerly The Foxboro Company). Use the info you obtain here at
> > > your own risks. Read http://www.thecassandraproject.org/disclaimer.html
> > >
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> >
> >
> > _______________________________________________________________________
> > This mailing list is neither sponsored nor endorsed by Invensys Process
> > Systems (formerly The Foxboro Company). Use the info you obtain here at
> > your own risks. Read http://www.thecassandraproject.org/disclaimer.html
> >
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>
>
> _______________________________________________________________________
> This mailing list is neither sponsored nor endorsed by Invensys Process
> Systems (formerly The Foxboro Company). Use the info you obtain here at
> your own risks. Read http://www.thecassandraproject.org/disclaimer.html
>
> foxboro mailing list: //www.freelists.org/list/foxboro
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>
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- » Re: [foxboro] FBM230/Modbus slave too fast problem [end of the story] - Pablo Lioi
