(1192 KB) Pobierz
Modbus Organization Newsletter, Summer 2010 
New Open‐Source Modbus 
A new open-source applications has been
listed on the
Modbus Technical Resources
— a free Ruby implementation of
the Modbus protocol. It supports Modbus
RTU and Modbus TCP as master or slave.
For the extensive list of all currently sup-
ported features please refer to the project
web site.
ProSoft’s New Modbus 
iPhone Application 
ProSoft Technology
announced the support
of the Industrial Hotspot series of radios in
conjunction with Sweet William Automation’s
new ScadaMobile application
for the iPhone/iPod platform.
The application provides engi-
neers with access to live proc-
ess control variables, and the
ability to modify this data re-
motely from their iPhones.
The app. creates a secure
wireless interface between an
iPhone and an existing 802.11
wireless network on the plant-
floor, allowing the iPhone de-
vice to read Modbus TCP and
EtherNet/IP process control variables from
programmable automation controllers/
programmable logic controllers (PAC/PLCs)
distributed throughout the plant. Live values
are displayed in lists and include user-defined
variance allowances and alarms. Engineers
can monitor these variables in real time and
make adjustments on the fly from an iPhone.
The combined security features offered by the
iPhone and ProSoft’s Industrial Hotspot radios
prevent unauthorized access to the network.
ProSoft’s new 802.11n industrial hotspots fea-
ture WPA2-PSK and 802.11i RADIUS security,
which prevent unauthorized access and modifi-
cation to the network. ScadaMobile also pro-
vides a security feature upon configuration
that requires the user to assign a matching
security code as both a password for network
access and as a Security Tag in the CPU.
When ScadaMobile launches, the security code
must match that on the CPU in order to create
a connection.
continued on page 4
Busy Summer for Modbus 
Member Companies 
It’s been a productive summer for Modbus Or-
ganization member companies. Here is a sam-
pling of the new Modbus products that came
out recently:
released Modbus Server firmware
announced the addition of
the new TRF-W to its line of meter-reading
released the VLT® Soft Starter
MCD 500
is offering ActiveX and .NET con-
trols for its Modbus TCP and RTU I/O Mod-
to learn more.
Wishing you all a
relaxing summer!
News about the World’s Most Popular Protocol 
Member News
Member News 
Member News
Member News 
is a leader in low-
power Field-Programmable Gate
Arrays (FPGAs) and mixed-
signal FPGAs. The company
offers a comprehensive portfolio
of system and power
management solutions.
Member News
Member News 
Deep Sea Electronics
Established in 1975, Deep Sea
Electronics has over thirty years
experience in creating market-
leading generator controllers.
DSE has a comprehensive range
of products, specializing in
automatic start generator
controllers, automatic mains
failure controllers, and auto
transfer switch controllers. DSE
has a technologically advanced
collection of load share and
electronic engine compatible
All products are
on-site at the
headquarters in
the UK. DSE
has an
additional office in North
America, as well as a
comprehensive global distributor
DSE has incorporated Modbus
RTU into its product line.
Frontline Test Equipment
is a
leading provider of PC-based
protocol analyzers for special-
purpose data communication
networks. Frontline pioneered
portable and versatile trouble-
Actel implements interface
standards in its products,
including Modbus, PROFIBUS,
WorldFIP, and P-NET.
The company’s products are used
in LCD control signal generation,
battery management, industrial
and medical equipment, and
military and aerospace
applications around the world.
shooting software solutions for
serial and Ethernet network
topologies and communication
The growing family of Frontline
Test System (FTS) general-
purpose and industry-specific
protocol analyzers is based on a
common protocol-decoding
engine. FTS products provide a
common user interface, offer
protocol decoding at the bit level,
and enable the rapid
development of custom decodes
for proprietary protocols and
extensions to existing protocol
decoders. Frontline’s Modbus-
related products include
Serialtest® and NetDecoder(TM).
Modbus Newsletter 
This is the newsletter of the
Modbus Organization, the
international nonprofit
organization devoted to the
evolution and support of the
Modbus protocols.
For more information about
membership and other services,
please refer to our website:
Newsletter Editor:
Lenore Tracey
Copyright 2010
Modbus Organization, Inc.
The Modbus Organization Mission 
The Modbus Organization, Inc. 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 Organization also provides 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
Member News 
Member News
Member News 
Member News
Member News 
Saving the Famous Bellagio Las Vegas Water Fountains from Extinction 
Dancing water is the signature
trademark of the Bellagio Ho-
tel, and last year it became
clear that keeping the water
show running might require a
major investment in an entire
new control system. The origi-
nal system was built around
several hundred pumps driven
by obsolete Danfoss 2200
drives using a proprietary pro-
tocol. The Bellagio avoided a
major investment by using a
Real Time Automation
way to interface Rockwell Auto-
mation POWERFLEX drives
with the legacy water fountain
control system.
In early 2009 it became clear that
the dancing water show at the
Bellagio Hotel, one of the most
renowned attractions on the Las
Vegas strip, was in peril due to
the obsolescence of the Danfoss
2200 drives used to build it in
The Bellagio was created to be
the pinnacle of opulence. Modeled
after the extravagant Lake Como
Resort in Bellagio Italy, the Las
Vegas Bellagio is a must-see for
every visitor.
With over 200 fountains, the Bel-
lagio fountain show is considered
the largest and most technologi-
cally advanced show of its kind in
the world.
The fountains are literally an
oasis in the desert. Fed by a well
once used to water the Dunes
Golf Course, which used to reside
on the same grounds, the foun-
tains use only 10% of the water
the golf course once used.
The fountains are powered by
220 pump houses located at the
bottom of the eight-acre lake.
The obsolete Danfoss 2200 drives
power pumps that send some of
the over 1,200 streams of water
as high as 460 feet in the air.
Over the years, the engineers at
the Bellagio scoured the globe
gathering all the 2200 drives
they could find, but by early 2009
it was clear that the supply was
simply running dry. Without a
replacement for the drives, the
show would soon come to a halt.
To make matters worse, the eco-
nomic recession had left Los Ve-
gas in a deep freeze as the num-
ber of visitors to Sin City plum-
meted. A low-cost replacement
option was needed to keep the
fountains up and running.
The possibility of simply replac-
ing the drives with more current
drives was quickly discarded.
Any other drive would have a
different communication protocol,
necessitating major changes to
the water show’s hardware and/
or software system. That would
be high risk and expensive, as
extensive time and testing would
be required. Plus there would be
no mechanism to phase in a few
at a time. The entire show would
have to go dark while all drives
and software were updated.
Instead, Real Time Automation
proposed a solution based on an
existing RTA gateway product.
RTA proposed customizing one of
its gateways to emulate the de-
funct drive so that none of the
show control software or hard-
ware would require modification.
Real Time Automation created a
solution that talked Modbus RTU
over an RS-232 port to a Rock-
well Automation POWERFLEX
drive, while communicating with
the legacy water fountain control
system using the DF2200 drive’s
proprietary serial protocol.
Using this module the Bellagio
solution was delivered within
days and functioned nearly per-
fectly during commissioning and
dry testing on land. The custom
protocol and logic for the DF2200
drive was added directly on top of
the established and tested Mod-
bus RTU code. This led to a much
shorter testing period and very
rapid advancement from beta to
production. The gateway module
made the POWERFLEX drive
appear to be a Danfoss 2200
drive, allowing seamless and effi-
cient integration — a true plug
and play replacement solution.
continued on page 4
Member News
Member News 
Modbus iPhone App. 
Member News
Member News 
Bellagio Fountains 
Once testing was
completed on land,
the solution had to
perform under wa-
ter. Installation in
this environment
was a daunting
three-day task.
Member News
Member News 
cont’d from pg 3
cont’d from pg 1
By using the ScadaMobile
application in conjunction with
ProSoft Technology’s Industrial
Hotspot series of radios,
engineers can manage their
industrial processes remotely.
The Industrial Hotspots are
certified for hazardous
environments and optimized for
plant-wide network integration,
particularly the new 802.11n
series, which is designed to meet
the specific needs of industrial
customers who demand ease of
deployment, ruggedness, and
reliable industrial
For plant engineers, this solution
Live monitoring of process data
for engineers and plant floor
Secure remote monitoring and
modification of live process
Real-time alarm management
First divers dove to
the bottom of Lake
Bellagio to discon-
nect the pump plat-
form from its power
and network connections. Then a small crane was floated over and the
15′ high structure was lifted out of the water and onto a raft. After it
was moved inside the facility, the platform was given 24 hours to dry.
Once dry, the drive solution was installed and tested. Finally the unit
was sealed, moved back, lowered into the lake, and connected to power
and the show controller.
With shows as often as 15 minutes a day, one day of testing confirmed
that the solution saved the dancing waters from extinction.
Real Time Automation supplies EtherNet/IP, Modbus TCP, Modbus
RTU and DeviceNet gateways to system integrators and end users
around the world. RTA also tailors these gateways for specific applica-
tions like the Bellagio Fountains. For more information on the com-
pany’s many Modbus gateways or for information on tailored applica-
tions like this, please visit the
Real Time Automation’s website.
Modbus humor courtesy of our
friends at
Member News
Member News
Modbus Discussion 
Modbus Discussion 
Q&A from the Modbus Discussion Forum... 
Most used Modbus Functions... 
Luca Gallina wrote to the fo-
I am developing a software Mod-
bus driver for S7-300/-400 PLCs,
getting rid of expensive
CP341/441 and their external
loadable drivers.
My personal experience on a few
cases tells me that almost no real
field applications require access
to memory area others than reg-
isters 30001.. and 40001.. (Most
requests are instrumentation and
DCS interfacing).
I am therefore focusing only on
Modbus functions FC03, FC04,
FC06 and FC16.
My question: In your real world
applications do you often (or
never) need to access Modbus
functions other than the ones I
listed above?
M Griffin replied:
I think it depends on the applica-
tion. If you are logging produc-
tion data then it’s usually just
registers. However, if you are
dealing with a simple HMI or
reporting status (is the machine
in auto, are there any faults,
etc.), then coils and (to a lesser
extent) discrete inputs get used a
If the software on the other end
is flexible, then it might be able
to use data in registers rather
than coils. However, some soft-
ware insists on having coils for
some functionality. That would
mean 1, 2, 5, and 15.
On the other hand, having regis-
ter-only access is still better than
having none at all.
Will you be doing a TCP version
as well as RTU? I’m assuming
this is RTU as you mentioned a
Harvard offered:
[Function] codes 1, 2, and 5 are
also a common offering on any
generic host. IMO.
Lynn August Linse suggested:
The other replies are good — but
I would avoid FC04. Some com-
mon client/hosts cannot issue
FC04 requests.
The bit functions FC01 and FC02
can be complex to create in a lan-
guage without shifts, because
literally you can read the 3rd to
6th bits, which must be shifted
over 3 places to return as-if the
1st to 3rd bits of a byte.
So I’d suggest:
1) FC 3, 6, 16
2) Make FC04 look like 3 (but not
sure the value of FC04)
3) Assuming all bits are READ-
ABLE via FN 03, then you don't
really need FN 1 & 2. I can't
think of any normal client/host
which could NOT handle bits re-
turned as packed blocks of 16 in
holding registers.
4) You could still do FN 05 to
write a single bit, as it is hard to
do bit writes via the FN16 since
you’d over-write 15 bits to
write 1.
Member News
Modbus Discussion
5) You could do FC15, but then
you are back to needing bit-
shifts. If they are easy to do fine,
otherwise skip the hassle.
Luca Gallina shared more in-
formation about his project:
Thank you for replies and opin-
1. Yes, I’m doing the RTU flavor.
2. My aim is to sell the S7 blocks
as communication libraries.
I haven’t planned a TCP driver
since I suppose it’s fairly simple
to send Modbus PDUs over
Ethernet. Most of the people
seem to have difficulties in creat-
ing the S7 code for generating the
CRC used in serial Modbus com-
Modbus users & suppliers 
get together on the  
Modbus Community for: 
Knowledge aggregation 
Contact with other 
Modbus users  
Discussion supported by... 
Zgłoś jeśli naruszono regulamin