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November/December 2008
Modbus Members Exhibit Modbus Conformance
at SPS/IPC Drives 2008 Test Program Update
Many Modbus Organization member
companies are exhibiting this week at
the SPS/IPC/Drives Show in
Nuremberg. Need a device that
“speaks” Modbus or advice on a
Modbus issue? Experts at these firms
are available to help.
A list of these companies and the halls
in which they can be found follows:
The true benefit of any open standard is the assurance it
provides to users that the products they buy will
interoperate seamlessly. Unfortunately, any specification,
no matter how carefully written, is subject to
interpretation and occasional misunderstanding. That’s
where conformance testing becomes valuable.
The Modbus Conformance Testing Program provides
independent verification that a broad array of
qualifications has been met in compliance with Modbus
specifications. It provides end users with the comfort
that their design and configuration process will proceed
smoothly and assures suppliers that their products were
developed in accordance with key Modbus criteria.
The Modbus-IDA Conformance Test Committee been
working on a revision of the test specification and test
A new test tool is expected to be announced and in
operation after the first of the year. At present,
conformance testing can be ordered through Modbus-
IDA with testing performed by approved third-party
test laboratories in the United States and China.
Request a conformance test order form by e-mailing
AFCON Software & Electronics
Control Techniques
Hirschmann Automation & Control
HMS Industrial Networks
Kepware Technologies
MESCO Engineering
Phoenix Contact
ProSoft Technology
Schneider Electric
Wachendorff Automation
7A-631, 6-244
9-225, 4A-542
1-440, 6-208
1-358, 6-210
6-328, 6-110,
10-230, 4A-520
6-410, 6-208
9-221, 9-125
9-339, 6-110
6-124, 6-324
7-130, 6-210
PHP Library for Modbus
UDP Master
A new project on the Modbus Organization
s Technical
Resource page ( is an
implementation of the basic functionality of Modbus
UDP using PHP. Implemented features include a UDP
Modbus master and Function Codes 3, 16, and 23.
Note that the site offers links to third-party
sites for Modbus users
and developers
These are not under the control of Modbus-IDA and
we are not responsible for the contents of any linked site
or any changes or updates to such sites. The inclusion of
these links does not imply endorsement of the site by
Modbus-IDA or imply approval of any content,
recommendation or application.
In anticipation of the
Thanksgiving Holiday
celebrated in the
U.S. this Thursday,
thank you to our
member companies
for your support and
good work!
News about the World’s Most Popular Industrial Protocol
Control Solutions, Inc.,
has been
developing networked control products
since 1995, specializing in building
automation, facility management, and
commercial automation. The company
offers a line of off-the-shelf embedded
control products with Modbus,
BACnet, Lon
, and SNMP
Meet Some of Our Members...
Organization News • Organization News
designs and
markets a
broad line
of devices
that enhance communication between
instruments, systems, machines and
other devices that use non-compatible
data protocols. The FieldServer
combined with its extensive driver
library allows users to acheive
Drivers included in the library are
Modbus, LonWorks®, BACnet,
Metasys, DH+, Profibus, and drivers
for fire alarm panels, controllers, and
many other devices. The primary
purpose of FieldServer products is to
allow communications over Ethernet
with delivery to client devices in a
format that is immediately useful to the
client device. Ethernet drivers include
Modbus TCP, BACnet Ethernet,
EtherNet/IP, BACnet IP, Allen Bradley
CSP, and more.
FieldServer products meet the
interoperability needs of facilities
managers and process control
engineers in industrial plants and
commercial buildings around the
Byres Security Inc.
develops industrial
security technologies for critical
infrastructure companies in the oil and
gas, power, chemical and
manufacturing sectors. Its sister
company, Byres Research Inc. is a
consulting and services company
providing security guidance on cyber
protection for critical infrastructures
and industrial processes to government
security agencies, major oil companies,
and power utilities. In October, the
company introduced the the Tofino™
Modbus TCP Enforcer Loadable
Security Module (LSM), the first
Control Solutions also provides custom
programming for standard hardware
and customized hardware solutions.
Control Solutions engineers each have
over 20 years of experience in
embedded controls technology. All
products are designed and made in the
USA and manufactured under ISO-
Control Solution’s Modbus products
include the i.Board®, a low-cost web
server for Modbus TCP as well as the
i.CanDoIt® web server series, which
includes Modbus support with a
powerful set of features, including data
logging, scheduling, alarm monitoring,
and e-mail notifications.
( www./
security module designed specifically
for managing the leading SCADA
protocol, Modbus TCP. The device
performs detailed analysis and filtering
of all Modbus TCP messages, and is
certified by Modbus-IDA.
Shouldn’t your
company be a
Modbus Newsletter
This is the newsletter of Modbus-IDA,
the international nonprofit organization
devoted to the evolution and support
of the Modbus protocols.
For more information about member-
ship and other services of Modbus-
IDA, please refer to our website:
Newsletter Editor:
Lenore Tracey
Copyright 2008 by the Modbus
Organization, Inc.
PO Box 628
Hopkinton, MA 01748 USA
ph +1-508-435-7170
fax +1-508-435-7172
The Modbus-IDA Mission
Modbus-IDA is a group of independent users and suppliers of automation
devices that seeks to drive the adoption of the Modbus communication protocol
suite and the evolution to address architectures for distributed automation systems
across multiple market segments. Modbus-IDA will also provide the infrastructure
to obtain and share information about the protocols, their application and
certification to simplify implementation by users resulting in reduced costs.
Member News • MemberNews
Afcon Announces Next-Gen SCADA/HMI
AFCON Software and Electronics
is revealing the next generation of
SCADA/HMI software – Pulse
SCADA/HMI – this week at the SPS/
IPC/Drives Show in Nuremberg,
Pulse is the most recent evolution of
AFCON’s P-CIM solutions for
SCADA/HMI. Pulse is designed for
the .Net framework. With increased
efficiency, superior visualization
capabilities, and a highly reliable
platform for production, it raises the
standard of SCADA solutions for
organizations of any size.
Pulse is a SCADA/HMI application
generator software that enables
application engineers to work in a
unified environment regardless of the
project deployment nature. It fits
standalone stations, networked
applications, Web architecture and
terminal service deployments, and is
also ready to run as client from flash
disk. The integrated development
environment supports the
transportability of application over any
.Net compatible platform such as
Windows XP/Vista and Server 2003/
2008 operating systems.
The Pulse Service-oriented Architecture
(SOA) is based on Microsoft’s WCF
technology, allowing remote distributed
concurrent engineering. Pulse relies on
the Microsoft ClickOnce solution to
enable remote client workstations to
update automatically with new product
versions and application definitions.
Taking advantage of .NET technology,
Pulse is integrated with a new look and
feel and various functionalities that help
controls and more can be added to the
product tools galleries and be reused in
the application.
To simplify connectivity from the plant
floor to corporate business systems
Pulse supports Microsoft SQL Server
2005 and OLEDB compatible
databases. Pulse operators and
managers benefit from the new
integrated Smart Information Panel
tool that provides out-of-the-box, real-
time, historical and alarm information
of any application tag, ready for
further data analysis.
Pulse supports over 200 protocols for
almost any device on the market,
including Modbus TCP and Modbus
over serial line, as well as the Unity
Founded in 1987, AFCON Software
and Electronics Ltd. is an international
software company and a leading
provider of SCADA/HMI systems
and solutions ranging from industry
control and building automation
management to OEM applications.
Pulse is the most recent
evolution of AFCON’s
P-CIM solutions for
SCADA/HMI. Pulse is
designed for the .Net
application engineers reduce design
time and lower total cost of
ownership. With Pulse’s new features,
users can develop professional
visualization screens using global smart
graphic objects, layers, themes and
Pulse leverages .Net technology
capabilities by granting advanced users
the option to extend the collection of
functionalities with software
components they develop themselves.
Components such as activities,
engineering unit conversions, .Net
Modbus-IDA Discussion Forums
Modbus Discussion
Sensors with Modbus TCP...
Emin Ceyhan requested advice
about sensors with Modbus TCP:
We need to use a sensor that supports
Modbus TCP. We have an RF Reader
Controller. The brand is Reva. One of
this electronic device’s features is
support of the Modbus TCP protocol.
If there is a sensor or transmitter with
Modbus TCP support, the sensor’s
message can be sent to Reva easily. Any
M. Griffin responded:
There are lots of “sensors” that work
with Modbus TCP. Unfortunately, you
are a bit vague as to what sort of
sensor you are looking for. If you are
looking for an RF antenna, then I
would suggest that you talk to the
people you bought the controller from.
Even if they don’t sell one themselves,
they can no doubt recommend one to
Emin Ceyhan provided more
information about his project:
Thank you for the response. I
understand you, but we have … to use
a sensor with Modbus TCP support. It
is a load-cell. So I need a transmitter
with Modbus TCP support.
M. Griffin replied:
So if I understand you correctly, the
“sensor” you are looking for has
nothing to do with the RF system itself.
You are looking for a load cell signal
conditioner with a Modbus TCP
I have seen “weigh controllers” with
network interfaces, including Modbus
TCP. For example Hardy Instruments
sells one.
I haven’t seen just a plain load cell signal
conditioner with any sort of network
interface. However, you can use a
standard load cell signal conditioner that
has an analogue output and connect it
to a network module that takes an
analogue input.
For example, Acromag has the 851T
From the Modbus Discussion Forum…
Strain Gauge/Load Cell Input, which
would interface to the load cell and
provide an analogue output.
They also have the 961EN/962EN six-
channel differential input: DC current
or DC voltage signals or the 963EN/
964EN 12-channel single-ended input:
DC current or DC voltage signals.
Either of these would take an analogue
input from the load cell signal
conditioner and output Modbus TCP.
I’m not recommending any of the
above products in particular, but I am
offering them as examples. There are
no doubt equivalents from other
manufacturers as well.
pvbrowser offered additional
I would suggest a Modbus TCP RS485
gateway such as [the Modbus Data
Gateway, ADAM-4572] http:// and
ADAM modules on RS485 as I/O
Add your advice to this thread at
Modbus TCP Data
Syed Hussain wrote to the forum:
We are using Honeywell Experion
C300 controllers to interface with VSD
drives for our expansion project. We
would be installing around 200 VSDs
all supporting Modbus TCP/IP
protocol. The Honeywell Experion
C300 controller can now talk peer to
peer with the Modbus TCP/IP slaves.
The only issue is that the controller can
only have eight Modbus TCP/IP
masters talking to eight Modbus TCP/
IP slaves. We are looking for a device
that can sit in the middle, acting as a
master for multiple VSDs and slave for
the Experion controller. Can someone
please advise if such a device is
available preferably Modbus-IDA
Mark suggested:
While it has never been tested with 200
devices, the PeakHMI RLL program
has Modbus TCP master and slave
included. It does not have a limit on the
number of connections. At the
moment it is free: http://
Michael Griffin offered:
I have a Free Software (GPL) project
called MBServer that can do this. It is
available at:
You will also find a link to it from the web site (Technical
Resources page).
You would use the mbserver (release 2)
package. There is introductory web-
based documentation at http://
The package itself has more detailed
web-based documentation available
through a built-in web server that is
accessible when you install it. I will be
adding the content of those additional
pages to the Sourceforge web site
within the next couple of days, so you
will be able to read them without
installing MBServer.
The software runs on a PC. There are
no limits to the number of client
(master) connections, but if you have a
lot of connections and are polling at a
fast rate you will want a fast PC to
handle the communications load.
Check the CPU load on your PC as
you add connections. If need be, you
could split the load between several
PCs. The software itself won’t cost you
anything, so it’s just a matter of how
many PCs you want to set up.
The size of the messages themselves is
relatively unimportant. What matters is
how many messages per second are
being sent and received. This means the
load on the slave (server) portion of
Modbus Discussion
From the Modbus Discussion Forum,
support Modbus TCP with master and utilizing. With Schneider Electric Altivar
the software will be relatively
61 and 71 drives it is possible to use the
unimportant, as you will be reading and slave modules. You would have to
I/O Scanner functionality of the
program the communications for
writing fewer larger messages.
various Modicon PLCs to accomplish
If you want to load test the PC, there is them, however, so it isn’t entirely out-
the task you are looking to do. The
of-the-box either. Whether you are
another package at the same location
DCS could then communicate to the
configuring MBServer or
called mbasyncserver that can be used
PLC and control the drives as required.
programming a PLC, I don’t see how
to act as just a slave (or you could just
you could avoid telling a system what
Syed Hussain:
set up a second instance of MBServer
addresses to read from what drives.
with no clients active). Set up
Thanks Fellows,
I would be careful about loading any
MBServer on one PC, and
We will be interfacing ABB LV and AB
system (including the Honeywell) to its
mbasyncserver on another.
MV VSD drives with the Experion
rated limit though. Often, the limit on
Then set the MBServer configuration
the number of connections allowed is a C300 controllers.
to open up 200 connections to
I have found information on an off-
mbasyncserver and do the same polling crude form of load limiting. The
the-shelf ABB LV VSD module called
processors in many PLCs (and other
commands you would use for the
NETA module that can talk Modbus
proprietary controllers) are relatively
drives. The reason for using two
TCP and can connect up to nine drives
slow, and they can get bogged down
different PCs is so that the second
on an ABB proprietary protocol called
with communications quite easily.
server isn’t adding its processing load
DDCS, which is what we are
Whether or not this would be a
to the same PC.
problem for you depends on how fast considering.
If you are interested and have further
you are polling.
So the DCS would be talking to the
questions, let me know and I will be
NETA card and NETA would be
Typically it is more efficient to transfer
happy to answer them.
talking to nine drives using DDCS
one large message than several small
Syed Hussain responded:
protocol on a fiber optic ring or star
ones. I would suggest trying to group
fiber optic topology.
I am more interested in a standalone
the messages from different drives
industrial grade device, preferably din-
close together in the memory of each
Does anyone have any idea about the
rail mounted that can act as a server.
data concentrator so you can read them DDCS protocol? I could not find any
We do not want to have all 200 devices all with one function call from the
decent documentation on the Net.
on the same server; 10 to 15 devices
We are still looking for a solution for
per server would be preferred to
Robert Willis suggested:
the Allen-Bradley MV VSDs, we are
reduce the risk of a single point failure.
considering an option like ControlNet
It would be beneficial to know the
Can you recommend a device that can
and then probably a ControlNet to
manufacturer of the VSD you are
serve this purpose?
Modbus TCP gateway. Any thoughts
on that? Any thoughts on
From Michael Griffin:
a solution that does not
I think what you mean is
involve a PLC in the
you want an “out-of-the-
Modbus users and suppliers get together
middle would be
box” solution. You could
on the Modbus Community for:
run MBServer on an
Add your advice to
industrial PC, and it
Knowledge aggregation
this thread, at
would be industrial grade
(including solid state drive,
Contact with Modbus users and suppliers
if you want).
Discussion supported by...
As for an out-of-the-box
solution, I don’t know of
a system that is exactly
what you want. You may
want to consider using
some small PLCs as data
concentrators. Quite a few
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