ISA2004Newsletter.pdf

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Modbus-IDA

the architecture for distributed automation

ISA 2004 Exhibition • Special Issue

News

intends to make this reformatting a

priority for the organization.

Jean-Jacques Poubeau, VP of Major

Programs at Schneider Electric and a

Modbus-IDA board member, also

commented: “Modbus, the only

industrial messaging protocol already

recognized by the Internet world (port

502) has one of the largest installed

bases worldwide with more than 7.2

million installed nodes. With this

positive vote, the Modbus TCP-IP

profile has been accepted by the IEC

as a Publicly Available Specification and

is now eligible to become part of

future editions of the International

Standards IEC 61158 and IEC 61784-

2. This is a significant step forward for

the efficient, proven and cost effective

Industrial Ethernet solution supported

by Schneider Electric.”

Modbus TCP Accepted as IEC

Publicly Available Specification

Modbus TCP put on “Pre-Standard” track

The ubiquitous Modbus protocol,

whose ownership was recently trans-

ferred from Schneider Automation to

an independent nonprofit organization,

Modbus-IDA, has been accepted by

the IEC as a Publicly Available Specifi-

cation (PAS).

The TCP variant of the protocol, along

with a companion protocol known as

RTPS, were submitted to IEC SC65C

as a real-time industrial Ethernet suite.

The submission was made possible by

the recent granting of a type D liaison

status to Modbus-IDA by the IEC.

Of 25 countries voting on the pro-

posal, there was only one negative vote,

reflecting overwhelming approval of

the specification. At the same time, the

specification was accepted as a New

Work Item by the subcommittee.

Modbus-IDA President Ken Crater

stated, “We are delighted to be the first

PAS to be approved during this

submittal period. Although our

organization is quite new, this approval

reflects the outstanding acceptance that

Modbus has received in the industrial

marketplace over the past 25 years.

More significantly, however, this

Publicly Available Specification repre-

sents our organization’s dedication to

bringing a new level of openness to

industrial communications.”

In approving the document, several

national committees asked for a

reformatting of the specification to

allow for better integration into the

revision of IEC-61158 (Ed 4.0 2007),

the well-known fieldbus standard.

According to Crater, Modbus-IDA

Schneider Automation Transfers Modbus Copyright to Modbus-IDA

We were delighted to announce the

recent transfer of the Modbus protocol

on April 12, 2004. In a dramatic move

signaling its dedication to the openness

of the Modbus protocol, Schneider

Electric transferred its copyright in the

protocol to Modbus-IDA. The agree-

ment, which was signed by Schneider

Automation, Inc., and Ken Crater,

president of Modbus-IDA, transferred

the protocol, including the entire “right,

title and interest” in the protocol

at the Hanover Fair trade show in

Germany.

According to Crater, “This transfer

establishes a milestone in the inevitable

migration of our industry toward open

protocols. It’s only fitting that the most

widely implemented protocol on the

industrial landscape is now in the hands

of a nonprofit organization committed

to its further proliferation and evolu-

tion.” Crater announced the

organization’s intent to pursue interna-

tional standardization for the protocol

in the near future.

Jean-Jacques Poubeau, VP of Schneider

Electric stated that “By transferring the

Modbus protocol rights to Modbus-

IDA, a nonprofit and independent

organization, Schneider Electric dem-

onstrates its willingness to move

toward really open systems and archi-

tectures based on open standards and

vendor-independent protocols. The

association of Modbus protocol with a

standard Ethernet TCP-IP stack makes

available the first really open and

vendor-independent Industrial Ethernet

solution.”

News about the World’s Most Popular Industrial Protocol

Standards Activities • Standards Activities

All the World’s Standards Groups Agree

Well, it may not be as momentous as

that, but five of the world’s Ethernet-

related standards groups, including

Modbus-IDA, signed a Memorandum

Of Understanding with IAONA at the

2004 Hanover Fair. The MOU pro-

vides the basis for the organizations to

work together under the IAONA

framework toward common solutions

to some of the remaining issues in the

design and management of industrial

Ethernet networks.

Key to the MOU is the fact

that there are still a number of

“white spaces” – that is, areas

in which the various standards

groups have not yet developed

divergent technologies – and it

is in these white spaces that the

organizations have agreed to

work toward agreement to

avoid further divergence of

practice. Some of the areas

anticipated by the MOU

include system issues such as

name space management,

security issues, cabling and the

use of IEEE 1588.

Organizations signing the MOU, in

addition to Modbus-IDA and IAONA,

include Interest Group SERCOS

Interface (IGS), Open DeviceNet

Vendors Association (ODVA), Ethernet

Powerlink Specification Group (EPSG)

and Ether-CAT Technology Group

(ETG). The agreement provides each

organization with a seat on the IAONA

Technical Steering Committee, and the

ability to participate in all IAONA Joint

Technical Working Groups.

RFC Process

Approved by

Modbus-IDA Board

In a move bringing the same standard

of openness enjoyed by the public

Internet to the world of industrial

standards, the Modbus-IDA board

recently approved an “RFC” (Request

For Comments) process for the

organization’s standards efforts.

The essence of the RFC process is to

encourage broad-based contribution

of new ideas into the standards-making

process, followed by periods of open

public comment and discussion.

Rather than the closed-door process

perceived by many to dominate in our

industry, this means that any change or

extension to Modbus standards will

take place in full public view with

opportunities for all points of view to

be heard.

The Modbus-IDA RFC is implemented

on the organization’s website, where

new initiatives may be submitted for

discussion. Also available on the

website is a flowchart document

illustrating the path taken by RFC

submissions.

Guiding the RFC process will be a

series of technical committees now

being formed by the organization (see

related story at right). These commit-

tees will work with RFC authors to

coordinate submissions of similar

intent, improve clarity of submissions,

assist in the integration of comments

and make recommendations for final

RFC approvals.

The technical committees will also be

able to initiate RFCs, to insure that

significant areas of technology are not

neglected in the Modbus-IDA evolu-

tionary process.

For more information on the RFC

process, refer to www.modbus-ida.org

and follow the link to “Modbus

Community - Developers Corner.”

The initial framework is now in place,

to be more fully populated as the

technical committees commence their

work.

The Modbus-IDA Newsletter

This is the newsletter of Modbus-IDA, the international nonprofit organization

devoted to the evolution and support of the Modbus and IDA protocols.

For more information about membership and other services of Modbus-

IDA, please refer to our website: www.modbus-ida.org

Newsletter Editor: Lenore Tracey

+1-508-435-7170

lenore@modbus-ida.org

PO Box 628, Hopkinton, MA 01748 USA

ph +1-508-435-7170 • fax +1-508-435-6929

info@modbus-ida.org

The Modbus-IDA Mission

Modbus-IDA is a group of independent users and suppliers of automa-

tion devices that seeks to drive the adoption of the Modbus communi-

cation 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.

Standards Activities • Standards Activities

Modbus-IDA Forming New Technical Committees This Year

Modbus-IDA is proud to announce the

initiation of its technical evolution

work, with the formation of five new

technical committees and a marketing

committee. This evolution will prima-

rily take place through the Request For

Comments process (see article at left).

These groups, composed of Modbus-

IDA members and invited guests, will

be primarily responsible for developing

and/or guiding extensions, modifica-

tions and supplements to the Modbus

specification as they progress through

the RFC process.

Most of the work will be accom-

plished via email, and most meetings

held via conference call, making it easy

for busy people to participate.

ments of certain application categories.

The effort may include the coexistence

6. Marketing.

Not a technical group, this committee is

engaged in the study of Modbus-IDA

marketing activities on behalf of its

members’ interests. Discussion to date

has focused on trade show activity, but

other initiatives such as regional work-

shops, publications and etc. will also be

discussed.

Any member interested in participating in any

of these committees is encouraged to contact

Ken Crater at ken@modbus-ida.org to get

more information or to sign up!

Members are being

welcomed now to help

with Modbus technical

evolution.

of Modbus TCP with conventional IP

traffic. Again, some of this effort

(notably IEEE 1588 implementation

and Ethernet frame prioritization) will

involve a liaison function with IAONA.

1. IT Infrastructure.

This group will work on system-level

issues, such as security, adoption or

adaptation of additional IP protocols,

application services, and network

installation, performance and manage-

ment. There will also be a liaison

function with relevant IAONA Work-

ing Groups.

Q&A

From the Modbus User Forum…

Store and Forward...

“I am told that this is not part of the

Modbus RTU protocol standard. Can

anyone with more expertise with

Modbus RTU protocol confirm this?”

Max Power replied: “The minimum

time to begin a response 3.5ct, but

there is no maximum. It could be 1

minute, 10 minutes, etc.”

Meir Saggie added: “A store & for-

ward mechanism is not part of

Modbus specs. (in particular, one that is

heard by the Master).

“In Modbus, the Master expects

precisely one reply to its query – good

or bad. In the latter case, the transaction

simply failed. It is up to the “user” of

Modbus to retry or not. (exception – a

Broadcast query does not expect any

reply.)

“In other words, the Master in your

case does not have the slightest idea of

where the ‘reply’ came from (the store

& forward machine in your case) – it

simply assumes it is from the slave and

processes it as such.

“As a practical solution, you may want

to insert a delay, so your Master is

‘deaf ’ for the amount of time the store

& forward machine ‘talks’.”

2. Conformance Test

Policy.

Already an active group, it’s purpose is

to further define and develop our

conformance testing program and

guide the efforts of our conformance

test lab(s). This includes the definition

of conformance classes and test

criteria.

3. Device Description.

The focus of this group is to work on

the structure and mechanisms to

associate semantics with devices. This

work may evolve to include many of

the former IDA Group issues, includ-

ing object definitions and distributed

automation.

4. Safety Layer.

This group is concerned with the

definition of a safety layer and related

conventions.

5. Real-Time.

This group will work on one or more

real-time solutions to meet the require-

On May 18, a user wrote: “In our

SCADA system the master transmits a

request message and then listens for a

proper reply message from a slave for

a timeout period of 1 second.

“With a store and forward implemen-

tation on a common radio frequency,

the master, after transmitting a request

message to the store & forward slave,

will ‘hear’ the store & forward station

request message and reply before it (the

master) receives a proper reply message

from the store & forward station.

“The Modbus RTU driver I am using

expects to receive a proper reply

message immediately after it transmits a

request message. If it hears anything

other than a good reply it sets a

timeout error code even though a

good reply is eventually received within

the timeout window.

“If the master receives a message or

messages that are NOT a proper reply

before it receives a message that IS a

proper reply, shouldn’t the Modbus

driver just ignore the improper mes-

sages and accept the proper reply

message if it is received before the

timeout?

Ask your question or help out another user on the Modbus Community Forums:

modbus.control.com for users or modbus.control.com/dev for developers.

Promoting Modbus • Promoting Modbus

Modbus-IDA at

ISA/2004

We’re looking forward to our next

successful trade show appearance at

ISA/2004, the enormously popular

U.S. venue for the controls and instru-

mentation industries. As in our previ-

ous booths, we’re putting our members

and their products on prominent

display, as the most compelling way of

demonstrating the overwhelming

popularity of Modbus in the industrial

world.

It Was Huge, and a Huge Success!

Modbus-IDA at Hanover Fair 2004

Making its first public appearance as

“Modbus-IDA,” our organization set

up shop for the week at the enormous

and impressive Hanover Fair. Our

efforts were met with great success,

and we carried our organization’s

message to many new companies in the

world automation market.

Five sponsoring members joined

Modbus-IDA in our debut appearance.

Our well-staffed booth featured the

products and literature of sponsoring

companies ACTL, HMS, Jetter,

Niobrara, and Schneider Electric,

whose representatives were joined by

Modbus-IDA President Ken Crater

and Executive Director Lenore Tracey.

Modbus expert Dr. Rudy Belliardi of

Schneider Automation was also on

hand to answer even the most difficult

technical questions posed by visitors to

our booth.

Two major events highlighted the week

for our organization. First was the

announcement of the transfer of the

Modbus copyright from Schneider

Automation to Modbus-IDA, a

milestone of monumental importance

to the move toward open protocols.

The second event was a signing cer-

emony at the IAONA booth. Repre-

sentatives of five major protocol

organizations signed a Memorandum

Of Understanding pledging coopera-

tion to avoid further divergence of

protocols in areas where standards do

not currently exist.

For the sponsoring companies, the

major event was the flow of current,

new and potential customers into our

booth and the forming of relationships

that will spell continued success for

years to come. We were happy to

make new friends with our booth

companions, and also happy to hear

that most of our booth partners will

join us in Houston for ISA/2004.

For Modbus-IDA, one of the greatest

values in our Fair appearance was the

opportunity to have in-depth discus-

sions with our member companies. We

come back from the Fair with new

ideas, new energy, and enthusiastic

commitments from numerous mem-

bers to participate in our technical and

marketing groups. We look forward to

working with you in the months and

years ahead to keep Modbus-IDA the

open and responsive organization it

was designed to be, and to keep the

Modbus protocol open and responsive

to the changes in our world.

This year’s booth at ISA will feature

displays by the following booth

partners:

• ACT’L

• Control Technology Corporation

• Harting

• HMS Industrial Networks

• Niobrara R&D

• Schneider Automation

Each booth partner will have a free-

standing kiosk with an overhead sign

and banner emblazoned with their

company’s identification. We intro-

duced a new Visibility Package with the

ISA/2004 appearance, and Precision

Digital and Scadaware are participating

at this level.

Join the Modbus-IDA

Marketing Committee

and help us help you!

Participate by email!

ken@modbus-ida.org

Modbus Products and Innovations

Acromag I/O Module Gains

Modbus Certification

Acromag, Incorporated

(www.

acromag.com), a Michigan-based

designer of analog and digital control

products for the industrial I/O market,

recently had its

BusWorks 900EN

Ethernet I/O Module

certified. The

product family consists of a variety of

analog and

discrete input/

output modules

for monitoring

sensors and

controlling

devices. Each

remote I/O

module provides

a 10/100

Modbus TCP/IP interface and up to

12 channels in an inch-wide unit. Major

features include 10/100 auto-negotia-

tion; configuration from a standard

web browser; and up to 12 channels

per stand-alone module. Analog inputs

accept TC, mV, RTD, VDC, and mA

signals; analog outputs provide VDC

or mA signals. Discrete I/O has 0-35V

DC range. An advanced/ruggedized

5-port Ethernet switch accessory is also

available in a compact 1-inch Din Rail

package. BusWorks 900EN Ethernet

I/O Modules have CE approval, UL,

cUL, and CL1 Div 2 Groups ABCD

approvals are pending. The product

comes with a five-year standard

warranty.

& UDP protocols and require no

proprietary cabling or network hard-

ware. Modbus function support

includes function codes 1, 2, 3, 4, 5, 6,

15 and 16.

When used in intelligent devices that

have their own micro-controller, the

AnyBus-IC is connected to the device’s

processor using a serial 2-wire TTL

interface. The AnyBus-IC is responsible

for the entire protocol handling so that

the microprocessor in the field device is

not tasked unnecessarily with bus

handling.

For use with simple processor-less

devices such as valve terminals and

modular I/Os, the AnyBus-IC has a

clocked shift register interface, which

can be directly connected to up to 128

input signals and 128 output signals.

The AnyBus-IC automatically detects

how much I/O data is connected to

the shift register during the Power On

phase. This makes it easy to implement

variable I/O configurations such as

those typically used in modular I/O

devices.

In addition to the Modbus-TCP

application protocol, the AnyBus IC

also has a wide range of embedded

Internet functions: embedded web

server with access to dynamic device

data and the possibility to embed Java

applets and scripts; on chip file system

with 1.4-Mb user memory for data and

programs; Telnet access, FTP file

transfer and functions for sending e-

mails.

The AnyBus-IC for Ethernet is an

addition to the AnyBus-IC device

family.

The 4201-MNET-MCM and 5201-

MNET-MCM gateways support RTU

and ASCII modes of Modbus, and can

be configured with up to 100 com-

mands per port, making it a very

powerful device interface and data

concentrator.

For more information on the 4201-

MNET-MCM or 5201-MNET-MCM,

email prosoft@prosoft-

technology.com or visit www.prosoft-

technology.com.

New Modbus Gateway

from ProSoft Technology

ProSoft Technology

has announced

its new ProLinx Modbus to Modbus

TCP/IP Gateways, the

4201-MNET-

MCM and 5201-MNET-MCM.

The

gateways provide interface communi-

cation for Modbus-compatible devices

to Modbus TCP/IP The Ethernet

communication port provides a high-

speed client and server connection.

Data is exchanged between the proto-

col drivers over an internal data file.

The Modbus TCP/IP client driver

supports the active reading and writing

of data with Modbus TCP/IP com-

patible devices. The devices support

standard TCP/IP support using TCP

HMS Industrial Networks

Introduces Modbus-TCP

on Chip

A new single chip-controller for

Modbus-TCP and embedded Internet

is available.

HMS’ AnyBus-IC

combines a powerful 32-bit micro-

controller with flash and RAM

memory, a 10/100 Mb Ethernet

controller and all the analogue functions

of an industrial-grade fast Ethernet

interface on a footprint of only 9 cm

The small size and reduced interface

costs now make it possible to imple-

ment an Ethernet interface for simple

field devices.

Check

out...

...the listings of Modbus

compatible products at

The chip is packaged in a 32-pin dual-

in-line case and requires only a 5 Volt/

250mA power supply. The Ethernet

interface provides 100 Mbps full

duplex data transmission, and the

integrated 32-bit microprocessor

guarantees short protocol processing

times.

www.

modbus-

ida.org

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