ModbusNews_Summer2006.pdf

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Summer 2006 Issue
News
Modbus in the
Wireless World
We’re not kidding when we say Modbus is everywhere. As
the most ubiquitous industrial communications
protocol in the world, Modbus is found in every
conceivable industry and application. Modbus
serial predominates in many legacy applications
and the number of Modbus TCP/IP applications grows as
Ethernet becomes the preferred communication medium.
The most recent space to find
Modbus is in wireless applications.
This is the focus of the Modbus
Organization’s exhibit planned for
ISAEXPO 2006.
We will be showcasing applications in four wireless
technology spheres. Member companies will be there to talk
about Modbus products in:
•
GPRS (General Packet Radio Service)
(Spectrum Controls)
•
Radio
(ProSoft Technology, Inc.)
•
802.11 (Wi/Fi)
(Sealevel Systems)
•
Bluetooth
(Schneider Electric)
Visit the Modbus-IDA booth to learn about devices and
applications in all four technologies. Members will display
their products and be available to help out with questions
about both wireless and traditional Modbus applications.
Modbus TCP/IP
IEC Update
Modbus-IDA Technical Director, Rudy Belliardi, has been
working closely with the IEC as the Modbus TCP/IP
protocol progresses through the process of review and
voting by member countries.
In September 2004, the protocol along with a companion
protocol known as RTPS, was submitted to IEC SC65C
as a real-time industrial Ethernet suite.
With the positive vote in 2004, the Modbus TCP/IP
profile was accepted by the IEC as a Publicly Available
Specification and eligible to become part
of future editions of the International
Standards IEC 61158 and IEC 61784-2.
In approving the document, several
national committees asked that the
specification be reformatted for better
integration into the revision of IEC-61158 (Ed 4.0 2007),
the well-known fieldbus standard.
Today, the reformatted specification has been submitted
for review, and the organization is awaiting comments
and requests for changes that will be addressed by a
deadline later in the year. After that, more review and a
final vote is expected in late 2007.
When this process is completed, Modbus-IDA plans to
make the revised protocol available on the Modbus-IDA
website as soon as possible.
The current version of the protocol is available on the
Technical Resources page , www.modbus.org/tech.php.
Visit Modbus-IDA
ISA EXPO 2006
October 17 - 19
Houston, Texas
Booth 2005
Members, join Modbus-IDA’s
Marketing Committee.
Help
steer the organization’s
marketing programs to best
serve your company’s needs!
e-mail info@modbus-ida.org
News about the World’s Most Popular Industrial Protocol
Organization News • Organization News
Meet Some of Our Members...
California-based
Automated
Solutions
develops OPC servers and
ActiveX controls for HMI and SCADA
development. The company offers
fully functioning
30-day trial
versions of all its
software products.
These include an
OPC Server for
Modbus/TCP
compatible devices,
OPC Server for Modbus RTU and
ASCII compatible devices, Modbus/
TCP Master ActiveX Control, Modbus
RTU and ASCII Master ActiveX
Control, Modbus Plus Master ActiveX
Control, and Modbus RTU/ASCII/
TCP Slave ActiveX Controls.
(www.automatedsolutions.com)
Hilscher
develops and manufactures
solutions for fieldbus and industrial
Ethernet, including PC cards, gateways,
ASICs for major systems such as
Modbus, Profibus, Profinet,
DeviceNet, CC-Link, InterBus,
CANopen, ControlNet, AS-Interface,
SERCOS, Industrial Ethernet, and
EtherNet/IP.
Hilscher’s PKV 30 Protocol Converter
provides protocol conversion between
different standard protocols such as
3964R, RK512, Modbus, Modnet, and
more.
(www.hilscher.com)
The
Central Power Research
Institute (CPRI)
is the power
house of the Indian electrical
industry. Set up in 1960 by the
Government of India, it functions as
a center for applied research in
electrical power engineering assisting
the electrical industry in product
development and quality assurance.
CPRI also serves as an independent
authority for testing and certification
of power equipment. CPRI’s
governing body includes
professionals from industry, utilities,
academic and research institutions,
and the government.
(powersearch.cpri.res.in)
The
Betec Engineering
development
team has extensive experience in
industrial electronics. They work
cooperatively on complex tasks in
hardware and software, bringing
innovative ideas to manufacturing
reliably and economically. Together with
the users, technical designers and buyers,
they define a project’s requirements,
then set their development engineers to
creating the new design, coordinating
hardware and software development
into prototyypes, optimizing the new
product until the prototype passes
testing and is ready for production. In
short, Betec offers technical support
during product and process
development; hardware and software
design, system development, and
housing prototyping.
(www.betec-electronic.de)
Modbus-IDA
see back cover for
details...
Join
Join!
Design!
Test!
Promote!
Apply!
Organization News • Organization News
Modbus Represented at Upcoming
MatrikonOPC User’s Group Meeting in Houston
Matrikon Inc.
will be sponsoring its
MatrikonOPC User Group
Conferences this fall. The conferences
are focused on “Driving Connectivity.”
They promise to provide practical
hands-on information for industrial
connectivity issues.
that is consistent with the architectures
and cost targets of industrial devices.
The Modbus protocol, originally
developed for serial device
communications, has successfully
migrated to industrial Ethernet
architectures due to its simplicity,
openness, and scalability. Modbus,
therefore, perfectly complements the
OPC architecture by allowing OPC
Servers to communicate easily and
efficiently to a full range of end devices
found in industrial applications
Other speakers at the conference
includes Dick Morley, father of the
programmable controller (PLC); Jim
Pinto, industry commentator; Tom
Burke, OPC Foundation President; Eric
Murphy, OPC Foundation HDA
Chairperson, and others.
Conference topics include:
•
Understanding the advantages
of implementing OPC technologies
•
Learning different OPC
specifications (OPC DA, A&E,
HDA, XML, UA)
•
Resolving common and advanced
DCOM problems
•
Securely passing Process Data
through firewalls
•
Increasing system interoperability
•
Automating Process Control
systems
•
Data exchange and amalgamation
•
SCADA Security
Phoenix Contact Inc.
develops and
manufactures specialized electronic
components and connection systems.
The company offers a diverse range of
products designed for industrial
applications including terminal blocks,
power supplies, signal conditioners,
industrial connectors, and automation
systems. Phoenix Contact has U.S.
headquarters located in Harrisburg,
Pennsylvania and world headquarters in
Blomberg, Germany.
(www.phoenixcon.com)
Trojan Technologies
is a leading
water treatment technology company
with the largest installed base of UV
systems in operation around the world.
It specializes in the design, manufacture
and sale of pressurized and open-
channel ultraviolet disinfection systems
for: municipal wastewater; municipal,
commercial and residential drinking
water; environmental contaminant
treatment; and industrial applications.
(www.trojanuv.com)
The MatrikonOPC User Group
conference has something to offer for
professionals from the plant-floor to
the boardroom. Sessions are designed
to equip attendees with intelligence for
users of all experience levels, with
tracks focused on OPC fundamentals,
advanced OPC integration and
corporate strategies.
Scheduled in Houston, Texas on
September 13 and 14 and Koln,
Germany on October 11 and 12, 2006,
MatrikonOPC, industry experts, and
end-users will present best practices,
lessons learned, case studies and
vendor-neutral solutions. Events
surrounding the conference dates
include OPC hands-on workshops,
Executive Standardization sessions,
SCADA Security Classes and interactive
panel discussions.
FSC, Inc.,
based
in Falls Church,
Virginia, is an independent software
vendor providing IT solutions for
property managers in the Federal
Enterprise. The company’s Federal Real
Property Management/Energy
Consumption application supports the
requirements of the Energy Policy Act
of 2005 and includes an EDI module
for processing invoices received from
utilities that are in electronic format.
FSC’s advance meter module uses
Modbus protocol to collect interval
data on an enterprise basis.
(www.govtproperty.com)
Modbus-IDA
will be at the conference
at both the table-top exhibition and as a
presenter. Fred Cohn, Modbus-IDA
president, will lead a session titled,
Modbus Protocol’s Openness and Simplicity
Complement OPC’s Power in Industrial
Ethernet.
He will focus on OPC as the industry
standard method for SCADA and
information systems to access plant
floor information. OPC’s Client/
Server architecture fits perfectly in the
PC environments hosting SCADA
systems. For OPC Servers to acquire
data from the plant floor, a simple,
cost-effective, open protocol is needed
Register for the
MatrikonOPC User
Conference
Dates:
Houston, TX – Sept 13-14
Koln, Germany – Oct 11-12
www.matrikonopc.com/opcug
Modbus Products and Innovations
Anybus X Gateways Translate
(almost) Anything
HMS Industrial Networks
picked the right name
when they developed the Anybus X series gateways. The
Anybus-X Gateways have been designed for use in harsh
industrial environments featuring standard DIN rail
mounting, IP 20 rating and 24-Volt DC power supply.
The Gateways are intelligent standalone devices supporting fanless operation and
industrial operating temperatures. The design is based on two embedded Anybus
communication modules and one additional gateway processor. Thanks to the wide
range of Anybus-S Slave and Anybus- M Master modules,
more than 150 Anybus-X
Anybus X Gateway
gateway combinations are available.
There is no programming involved. You
simply choose the gateway version that supports the two networks you want to
bridge. For each of all possible network combinations, there is a separate gateway. The gateway concept primarily focuses
on the transfer of cyclic I/O data between two networks. During the set-up of the gateway, you select the amount of
I/O to be transferred between Network 1 and Network 2. Since industrial networks support different amounts of I/O
data, the network with the smaller amount of I/O data determines how much data can be transferred in each case.
The Anybus-X Gateway product family supports 17 different Fieldbus networks. The Anybus-X Gateways help control
systems integrators to interconnect any two networks enabling consistent information flow throughout the entire plant.
For more information, visit www.anybus.com.
Modbus Port Expander Plus
Phoenix Digital’s Modbus Port Expander Plus (MPE+) product operates as a Modbus
Multi-Master Multiplexer, network server, and communication controller all in one.
Phoenix Digital’s Modbus Optical Communication Modules (OCMs) provide multidrop
fiber optic communications for high reliability Modbus communications. The MPE+ and OCMs are available in modular
standalone, panelmount enclosures and 19-inch rackmount/panelmount enclosures with integral 120/220 VAC, 24 VDC, or
125 VDC power supplies. Modbus Port Expander+ features include:
• Multi-Master Multiplexer
Muliplex up to 8 Modbus Masters with a Single MPE+
Cascade multiple MPE+ units for additional Modbus Master Multiplexing capability.
• Self-teaching, real-time database
Instantaneous Modbus Response
No-Wait Screen Updating.
• Hot standby, failsafe operation
• Peer-to-peer Modbus Communications
Communicate directly between Modbus slave devices
• Host-to-Host Modbus Comunications
Communicate directly between Modbus host devices
Modbus Port Expander
• Interfaces dissimilar Modbus devices
On-the-fly conversion of all Modbus communication parameters, including ASCII/RTU
For more information, visit www.phoenixdigitalcorp.com.
Modbus-IDA Discussion Forums
Q&A
Newbie Question on Register
Assignments...
On June 10th Ed Francy asked,
I am starting development of a
Modbus slave. Is there some standard
for mapping Modbus registers for
configuration and measurements? How
is a Modbus master configured to use
these if I just assign them any way I
wish?
I have implemented a HART slave
previously, and HART controllers have
a special language (DDL) for defining
how HART masters interact with slaves.
Is there anything like this for Modbus?
All the specs. I have found on the
Modbus protocol define just the
protocol, not specfics about how to
map your device’s I/O. Am I missing
something?
Another question - must I do the
“multiply floating point values then
divide on the other end” method to
transfer floating point values? Or can I
transfer a 4 byte floating point number
with two register reads?
Dweebyone replied,
There are 4 basic types of register in
Modicon Modbus:
• 0x register represents a digital output
• 1x register represents a digital input
• 4x register represents an analogue
output (16 bit)
• 3x register represents an analogue
input (16 bit)
Only the Modbus master can initiate
communications. The Modbus master
can request data from any slave on the
network. It should receive a reply from
the slave in question. You can also
broadcast i.e., send a request to ALL
the slaves on the network. When
broadcasting, no reply is given to
master.
There are various Modbus “Function
codes” that specify what the master is
From the Modbus User Forum…
asking of the slave. For example, you
may wish to read one off 1x register,
or multiple 1x registers. There would be
a different function code for these two
instructions. There are various function
codes for reading/writing or both, for
0x , 1x, 3x, and 4x type registers.
See www.modbus.org for more info.
An anonymous poster commented,
Modbus is the protocol (language) that
you use to communicate to the device.
The address assignments are a function
of the device you are working with and
they vary.
Modicon addressing (which is a
standard since it was associated with
Modbus initially) uses the first digit to
determine if it is a digital or analog
input/output and the other digits for
the addressing.
With PLCs, which allow you to address
the I/O as you like, my experience is it
is preferable to start your hardware
addressing (input/output modules)
from the lowest address and keep the
addresses contiguous. Allow for future
expansion if required.
If your device isn’t flexible then you
have to use the addressing that they
have configured.
Another user suggested:
Masters come in different shapes,
forms, and flavors.
Some Modbus masters have the ability
to read contiguous slave registers as a
“block.”
So you want to consider which slave
registers might be most useful to the
master client and designate them as
contiguous registers. Leave the rarely
used or esoteric value registers on the
periphery of the slave map.
Modbus RTU to Ethernet...
On June 15th, Carsten Roll wrote:
I want to talk to some meters using
Modbus RTU across Ethernet. I have
an RS 485 serial to Ethernet converter.
Is that possible with the device? Or do
I need a special Modbus Ethernet
converter? I have the ADAM 4570
from www.advantech.com, but I am
wondering why they sell a special
Modbus Ethernet converter. My
Modbus network is a 2-wire RS485.
bscook replied,
The single biggest factor in determining
compatibility with converters is timing.
Since Ethernet is packet-based, it can
impose delays into the serial stream.
Modbus RTU doesn’t tolerate delays
greater than 13 ms. This should be fine
for most adapters on the market,
provided that network routing is kept
to a minimum. This involves the
physical and virtual architecture (e.g., if
you’re trying to maintain control across
a companywide network or (worse)
the Internet, you’ll have troubles,
especially if you have a busy network.)
Also, if your network administrator
permits it, converters in UTP/IP mode
are faster, have less overhead, and
provide the kind of timing you likely
need. Many network admins don’t
permit it, because it floods the network
with traffic.
If you have a managed network, your
admin can probably set it up to permit
UTP/IP across whatever segments
you’ll be using, without letting it flood
the rest of the network.
The downside of UTP/IP vs TCP/IP
is that it is more likely to introduce
errors into the data stream over very
large packet-switched networks, but is
generally just fine in smaller networks.
To follow this discussion further, go to
modbus.control.com/1026223137
Ask your question or help
out a fellow engineer on the
Modbus Discussion Forums:
modbus.control.com

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