Re: [foxboro] Telemetry

I guess I wasn't clear in my use of terminology.

A Modbus Slave is a device that responds to data requests from a Modbus
Master.

The Modbus protocol supports multiple stations on the wire, but only one of
those stations is the Master. That is, only one of them can initiate data
transfer. The others (the Slaves) wait for instructions.

Configuration of the PLC (or other target) is a completely different topics
and the I/A Series does not offer products to configure end devices through
the various interfaces.



Regards,

Alex Johnson
Invensys
10707 Haddington
Houston, TX 77063
713.722.2859 (office)
713.722.2700 (switchboard)
713.932.0222 (fax)
ajohnson@xxxxxxxxxxx <mailto:ajohnson@xxxxxxxxxxx> 
Shop at the I/A Store and Save on all Invensys Products - www.iastore.com
<http://www.iastore.com> 
Come to the Invensys Showcase: http://www.invensysshowcase.com/
<http://www.invensysshowcase.com/> 


        -----Original Message-----
        From:   Loyd Greer [SMTP:lgg@xxxxxxx]
        Sent:   Thursday, August 15, 2002 8:15 PM
        To:     foxboro@xxxxxxxxxxxxx
        Subject:        Re: [foxboro] Telemetry


            Thanks Alex,

             I believe what I will need is just a slave. Configuring the
controller
        and remote terminals is done by another group. I feel just fine
letting them
        maintain that responsibility. We are reading a PH at the wells and I
will
        have to find out if that is an integer or floating point.

            Loyd Greer
            Great Lakes Chemical

        ----- Original Message -----
        From: "Johnson, Alex (Foxboro)" <ajohnson@xxxxxxxxxxx>
        To: <foxboro@xxxxxxxxxxxxx>
        Sent: Thursday, August 15, 2002 3:52 PM
        Subject: Re: [foxboro] Telemetry


        >
        > Number one on the list of things to worry about - The choice of
Modbus I/F
        > from the I/A Series.
        >
        >
        > There are two for serial links:
        >
        >
        > * The PSS 21H-7G4 B3 <21h7/21h7g4b3.pdf>  Integrator 30, Style B
for
        > Modbus Devices which speaks pure unadulterated Modbus and
        > * The Modbus Device Integrator from Ken Gunston's group which can
        > handle almost any Modbus based device.
        >
        >
        > As an example of the differences:
        >
        >
        > * The Integrator 30, Style B for Modbus Devices is a Modbus Master
        > only. The MDI can be either Master or Slave.
        > * The Integrator 30, Style B for Modbus Devices doesn't handle
        > floating point values (only scaled integers (counts) are
supported). The
        MDI
        > can handle 32 bit floating point values.
        >
        >
        > I'll send you a check-off list that I've used before to qualify
the choice
        > of Modbus interface under separate cover. It is not perfect, but
it is
        > useful.
        >
        >
        > Regards,
        >
        > Alex Johnson
        > Invensys
        > 10707 Haddington
        > Houston, TX 77063
        > 713.722.2859 (office)
        > 713.722.2700 (switchboard)
        > 713.932.0222 (fax)
        > ajohnson@xxxxxxxxxxx <mailto:ajohnson@xxxxxxxxxxx>
        > Shop at the I/A Store and Save on all Invensys Products -
www.iastore.com
        > <http://www.iastore.com>
        > Come to the Invensys Showcase: http://www.invensysshowcase.com/
        > <http://www.invensysshowcase.com/>
        >
        >
        > -----Original Message-----
        > From: Loyd Greer [SMTP:LGREER@xxxxxxxx]
        > Sent: Thursday, August 15, 2002 2:14 PM
        > To: foxboro@xxxxxxxxxxxxx
        > Subject: [foxboro] Telemetry
        >
        >
        > Hi,
        >
        >      I am looking at adding 3 Zetron Model 1700 controllers with
        > about 120 =
        > RTU's to our IA system with a CMP30B interface. I would like to
ask
        > if =
        > anyone has done this with a Zetron controller and if so what
        > pitfalls I =
        > might look for.=20
        >      =20
        >      The model 1700 uses modbus RTU protocol. =20
        >
        >       <<<Loyd Greer>>>
        >              Great Lakes Chemical Corp
        > =20
        >     =20
        >
        >
        >
        >
        >
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