ModbusNews_ARC2005.pdf

(389 KB) Pobierz

Modbus-IDA

the architecture for distributed automation

In a striking affirmation of the ubiqui-

tous Modbus protocol, the Standardiza-

tion Administration of China (SAC) has

formally launched the following three

standards for industrial automation in

the People’s Republic of China:

GB/Z 19582.1-2004 Modbus Industrial

Automation Network Specification Part

1 – Modbus Application Protocol,

GB/Z 19582.2-2004 Modbus Industrial

Automation Network Specification Part

2 – Modbus Protocol Implementation

Guide over Serial Link, and

GB/Z 19582.3-2004 Modbus Industrial

Automation Network Specification Part

3 – Modbus Protocol Implementation

Guide over TCP/IP.

ARC Forum 2005 • Special Issue

News

have been working closely with

Schneider Electric as they develop and

propagate the use of standards in their

industrial infrastructure. In conjunction

with launching the Modbus standard, a

conformance test laboratory is antici-

pated to open in China within the next

few months.

Ken Crater, president of Modbus-IDA,

noted, “It makes sense that the Chinese

industrial market adopt Modbus as its

fieldbus standard. Simplicity and ease

of integration make it a natural choice.

The fact that it is already widely used in

China was also an important factor in

the standardization decision.”

Modbus Accepted as Chinese

Standard

Mr. Ouyang Jinsong, Director of

Standardization, Department of

Instrumentation Technology &

Economy Institute, People’s Republic

of China, and General Secretary of the

National Standardization Technical

Committee on Industrial Process

Measurement and Control, confirmed

the standards were effective October

26, 2004.

The news was welcomed by Modbus-

IDA, the international organization for

suppliers, implementers and users of

Modbus and its companion protocols.

The Chinese standardization authorities

Modbus-IDA at ISA EXPO 2004

Modbus-IDA opened for

the third year in a row at

ISA EXPO with an

expanded presence in more

ways than one. In a 400-

square-foot booth,

Show

Partners

ACT’L, Control

Technology Corporation,

Harting USA, HMS

Industrial Networks,

Niobrara R&D, and

Schneider Electric met with

customers, prospective

clients, and fellow exhibitors

to showcase their Modbus-

based products.

With more than twice the

number of members as this

time last year, Modbus-IDA

promoted its own activities

and its members. The booth

featured a 20-foot-high multi-colored

banner display and a presentation that

illustrated the organization’s growth and

its members’ logos on an 8 x 8 foot rear

projection screen suspended over the

main aisle.

Members Precision Digital Corporation

and Scadaware participated through the

organization’s

Show Visibility

Program, which allowed Precision

Digital to augment its presence in its

own booth elsewhere in the show.

Scadaware, one of Modbus-IDA’s

systems integrator members, took

advantage of this program to meet with

customers and chat with visitors

looking for expert assistance solving

challenging applications problems.

(continued

inside back cover)

News about the World’s Most Popular Industrial Protocol

Standards Activities • Standards Activities

Modbus-IDA Technical Committee News

Modbus-IDA’s technical committees are

now actively working in several areas.

The

IT Infrastructure

group had its

first meeting in November 2004.

Chaired by Dominic Iadonisi of

Hirschmann Electronics USA, the

group began to lay out issues on which

it plans to focus. These include:

•

Types of identified networks (e.g.,

standalone, non-interlocked);

•

Network topologies (daisy-chain,

tree, mesh, ring, star);

•

Required switch support (port

autonegotiation, auto cross, 10/

100);

•

Desired switch requirements (e.g.,

SNMP, traffic thresholding, port

mirroring);

•

Standard LED requirements;

•

Alarm signal contact requirement;

•

Redundant power inputs; and

•

Specifications for cable types and

connector types, for both copper

and fiber cables

The group plans to meet again during

Q1 2005. Please contact Modbus-IDA

by e-mail if you wish to join

(info@modbus-ida.org).

The

Conformance Test Policy

group

has been meeting monthly to further

define and develop Modbus-IDA’s

conformance testing program. In

recent discussions, the group has

elected to suspend the Conformance

Test Program and redesign it, adding

some physical layer testing and consid-

ering more options for interoperability

testing. Additional work on conform-

ance testing for Modbus over serial line

is also underway.

The group is considering a self-test

option, which would allow companies

to purchase the test suite and certify

devices under a strict set of require-

ments. Devices certified under the self-

test option would be identified by a

separate certification seal. An outside

test laboratory option will still be

available for those companies desiring

third-party certification and to verify

the validity of self-test program

operations.

Technical

Committees Work

on Modbus’ Future

Join one of

Modbus-IDA’s

technical groups:

IT Infrastructure

Conformance Test

Policy

Device Description

Safety Layer

Real Time

Contact Ken Crater

(ken@modbus-ida.org)

for more information

or to join a Modbus-

IDA committee or

technical group.

The Modbus-IDA Newsletter

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

tion 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

Your Website

Ideas are needed!

In an effort to make more Modbus

information available to you more

easily, we are redesigning the

Modbus-IDA website. We are

adding more product announcements,

more device listings, more news.

E-mail any ideas you have for

features, functionality, or other

useful information for Modbus users

and developers to info@modbus-

ida.org. We look forward to making

the website work for you.

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 communica-

tion protocol suite and the evolution to address architectures for distrib-

uted 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 implementa-

tion by users resulting in reduced costs.

Standards Activities • Standards Activities

Q&A

From the Modbus

User Forum…

Modbus frames: serial vs. TCP...

Sentekin Can wrote: How does serial

Modbus message, which is variable

length, form into fixed length Ethernet

frame?

Jiri Baum replied, “The TCP part of

TCP/IP simulates a continuous

connection. Just ignore the whole frame

thing and send your data. The TCP/IP

stack will break it into packets, send

them, retransmit them if they get lost

or corrupted, etc.”

Another reader suggested, “Modbus

TCP is Modbus RTU that has been

enveloped into a TCP data header.

Layer 1-6 is all TCP/IP data header.

Layer 7 is the application layer, which

holds the Modbus RTU data frame.

The only difference is that NODE

ADDRESS=1 as default.

“Function code is Modbus function

code to read or write same as RTU;

target register is the same as RTU;

number of registers is same as RTU;

data out is same as RTU and data in is

same as RTU; and the CRC check is the

same as RTU. The Modbus message is

not fixed. Many people will send a

Modbus TCP message over Ethernet to

serial converter, which strips out the

TCP/IP header and sends the Modbus

RTU message to the remote serial

device. By changing the Node address

to the remote node address this makes

it possible to communicate to serial

devices over Ethernet.”

Lynn Linse added, “I am not sure what

you mean by ‘fixed length Ethernet

frame.’ Ethernet has a minimum size to

enable collision detection (I think it’s 64

bytes?). However the link, IP, and TCP

headers occupy most of this. Any

Modbus/TCP message will be larger

than this min size.

Max Modbus serial message is 255 bytes

(3 + 250 + 2); Max Modbus/TCP

message turns out to be 259 bytes (6 +

3 + 250); Max Ethernet frame is 1500

bytes (given no fragmentation). So

Modbus creates no size problems under

Ethernet.

“Or perhaps you mean since Modbus

RTU’s length is ‘felt out’ by watching

for time gap; how is Modbus/TCP

length detected? The Modbus/TCP

header includes a length byte, so it is

explicitly defined within the first six

bytes.

“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’.”

Gregoire Belliveau wrote to the Forum:

“We are looking for information about

running Modbus TCP/IP over a

satellite network. Our network typically

has a 590-ms round trip delay time. We

are looking at running GE’s Multilin

software communicating to various GE

MultiNet (or similar) devices at the far

end. As for the MultiNet, we believe

that a device with remote IP

programming ability (similar to

Lantronix) would be a better fit. Any

suggestions here?î

Rainer Lehrig answered, “The Modbus

protocol works with request/response.

Thus you will have a big delay because

of your round trip time.

“It would be better to implement a

more intelligent server(s) at the local

places. These server(s) could talk to

Modbus. e.g., read your variables

Ask your question or

help out another user

on the Modbus-IDA

Community Forums.

For users:

modbus.control.com

For developers:

modbus.control.com/dev

Modbus TCP/IP over Satellite Nework...

cyclically and send them to your remote

site without request/response. Only

send data across the satellite network in

one direction!

John Rinaldi responded,

Have you

tried it yet? I can’t think of any reason

why it wouldn’t work. There are two

timeouts to consider. One, the TCP

connection timeout. This is typically in

the neighborhood of two seconds. The

other is of course the Client timeout.

What kind of trip time will the satellite

give you? Can you modify these

timeouts to be 20-50 percent more than

the trip time?î

Finally, Micahel Weaver suggested, “You

should go to industrial standard TCP/

IP configuration and you should [have]

no problem with communication. It

would be transparent to the processor.î

Modbus Products and Innovations

Prosoft Technology Helps Take

Out the Ash

A thermal power station in Mexico needed Modbus communication between

Allen-Bradley PLC5 processors and the pneumatic transport system for light ash.

The hot light ash is retained from flue products and discharged into special

containers, which are

dfdfdf

air into a larger bin. The system also consists of

emptied by

compressors, fans, and air filters. Once the ash is placed in the bin it is

transported to either an ash disposal area or to a cement works for cement

production.

The system is very sensitive to control system outages. If a failure occurs, pipes

can be filled with hot ash, which will harden. To avoid outages, the system was

equipped with a redundant processor.

The control system was a redundant solution of PLC5s communicating over a

ControlNet bus with RIO modules.

System Integrator, AUTEL knew that since Modbus was the communication

protocol between the PLC and the DCS supervisory system, a Modbus

Communication Module was needed. Autel selected the Prosoft 3100-MCM. A

3100-MCM, functioning as a Slave, was placed in each PLC. The 3100-MCM

modules contain two ports.

HMS Releases FIPIO and

ModbusRTU Slave Versions of

Anybus Communicator

The addition of FIPIO and ModbusRTU on the fieldbus side of the Anybus

Communicator extends the gateway concept to a total of nine different

fieldbuses.

The ModbusRTU slave side is available for both RS232 and RS485.

The AnyBus Communicator Gateway is an external DIN-rail mounted gateway

that provides fieldbus network connectivity on one side and a configurable serial

interface on the lower side, e.g., Modbus RTU master. The gateway can therefore

work as a data concentrator on a Modbus network being Modbus RTU master on

one side and a Modbus RTU slave on the other side.

In the sub network side it has serial protocol support for Modbus RTU Master

Mode and Generic Data Mode, which is fully configurable through the ABC

Config Tool for Windows and the

configuration port on the AnyBus

Communicator. Other protocols can be

implemented by HMS on request.

Check

out...

...the listings of Modbus

compatible products at

www.

modbus-

ida.org

Modbus Products and Innovations

Sealevel Systems I/O

Device Certified

Sealevel Systems, Inc.

(www.sealevel.com), recently submitted

the

SeaI/O™

for Modbus conform-

ance testing. The South Carolina-based

company has manufactured quality

Serial and Digital I/O products since

1986.

The SeaI/O is a modular I/O system

that offers

selectable

connectivity

and a wide

variety of I/O types for distributed

control and data acquisition require-

ments. An array of configurations is

available, each designed for maximum

flexibility and easy field wiring. Order-

ing options allow connection to the

host device via Ethernet (Modbus/

TCP), RS-485 (Modbus/RTU), USB, or

RS-232 (Modbus/RTU). SeaI/ O

modules are designed for a wide variety

of applications and environments

including process control, data acquisi-

tion, broadcast automation, security,

and facility management. I/O models

offer a choice of optically isolated

inputs, Reed relay outputs, Form C

CTC Releases Enhanced

Web-Enabled Controller

Technology Corporation

(www.ctc-

control.com) has added the

Model

5200

to its

Blue Fusion™

line of web

enabled automation controllers. The

Model 5200 features a built-in web

server, enabling users to securely

monitor, control and upgrade processes

via Internet access. The unit also

includes multi-unit expansion racks to

allow users to control larger

applications with more I/O with a

single CPU and control strategy. A

single Blue Fusion system can now

Hopkinton, Mass.-based

Control

Acksys Introduces OEM

Serial to Wireless

Ethernet Module

ACKSYS Communications

(www.acksys.com) widens its range of

wireless solutions by introducing a serial

to Ethernet WiFi

module for the OEM

market.

The product relies on

the IEEE 802.11b

standard (2.4 GHz)

and is IEEE 802.11g-

compatible. It features a high-speed

serial interface (up to 250 Kbps)

available on a SUBD 9 connector for

RS232 model or on a 16-pin HE10

connector for the TTL model.

It can be powered from the DC power

source (+3.3VDC or +5VDC); con-

sumption doesn’t exceed 3W.

This module supports TCP Client/

Server, TELNET RFC2217, COM port

redirection, TELNET server, raw,

point-to-point and the serial Modbus-

to-MODBUS/TCP gateway.

The device is administered over a web

browser or with TELNET.

Blue Fusion Model 5200

SeaI/O

relay outputs, and TTL interface to

industry standard solid state relay racks.

Field removable terminal blocks are

standard, facilitating fast, flexible field

wiring. SeaI/O modules operate from

9-30VDC, and power can be input via

terminal block or DC jack. Both table

mount and DIN rail mounting options

are available, and configuration is made

easy using Sealevel’s software tools.

control up to 192 I/O points and up to

six axes of motion.

Bi-directional e-mail support lets the

Blue Fusion controller send alerts or

production data in an e-mail message.

Users can also send an e-mail to the

Model 5200 with customized

instructions to modify the controller’s

operation.

The Model 5200 supports UDP, TCP/

IP, HTTP, and Modbus TCP Master/

Slave. Through DHCP support, the

controller can be named and appear like

any other node on the network. The

Model 5200 can additionally be set up

as an FTP server for upgrades, support

or for propagating control strategies

from one control unit to others.

WL-Dongle-OEM

Plik z chomika:

TirNaNog

ModbusNews_ARC2005.pdf

Plik z chomika:

Inne pliki z tego folderu:

Inne foldery tego chomika: