ABB AC800M PROFIBUS DP Installation System

ABB AC800M  PROFIBUS DP Installation System

Fieldbus systems are used as a means of communications for serial data exchange

between decentralized devices on the field level and the controller of the process

supervision level.

PROFIBUS means PROcess FIeldBUS, designed as a fieldbus for process

automation purposes for interconnecting Decentralized Peripheral devices

(PROFIBUS DP), and its extended version for Process Automation (PROFIBUS

PA). It is well known all over the world and the most popular fieldbus in Europe.

Due to its high data transmission rates over short distances and moderate ones over

long distances it is predominantly used for interconnecting I/O units like S800 /

S900 or smart devices to PLCs and controller like AC 800M.

This user manual provides a brief overview of the PROFIBUS technology, to help you

by planning, commissioning and testing. It does not release you from the necessity to

observe the relevant standards. The valid version of the EMC directive and other

PROFIBUS guidelines and the shield and grounding directives, particular for

PROFIBUS-PA must be observed.

PROFIBUS is a manufacturer-independent fieldbus standard for applications in

manufacturing, process and building automation. PROFIBUS technology is

described in fixed terms in DIN 19245 as a German standard and in EN 50170 / IEC

61158 as an international standard. It specifies the technical and functional

properties of a serial bus system. The PROFIBUS standard is thus available to every

provider of automation product.

PROFIBUS distinguishes between master and slave. The masters determine the data

communication on the bus. A master can send messages without an external request

if it has access rights to the bus (token). The slaves are peripheral devices. Typical

slaves are I/O devices, valves, motors and transmitters. They have no bus access

rights. They can only confirm received messages or send a message on the request

of the master. Slaves are passive devices on the PROFIBUS.

PROFIBUS is composed of three types of protocol, each of which is used for

different tasks. Of course, devices with all three protocols can communicate with

each other in a complex system by means of a PROFIBUS network.

The three types of protocols are: PROFIBUS FMS, DP, PA.

Communication Protocols

At the protocol level, PROFIBUS offers a broad spectrum of options, which enables

optimum communication between different applications. PROFIBUS DP is a fast

and deterministic process data exchange between a PROFIBUS master and the

assigned slave devices.

Presently the basic and extended functions supported with AC 800M/CI854(A) are:

• Basic function (V0):

– Cyclic data transfer

– Diagnostic

– Configuration via GSD files

• Extended function V1:

– Acyclic data transfer

– Alarm handling (planned, but not supported yet)

– FDT/DTM device management

– Function blocks acc. IEC 61131-3

RS485 installation recommendation

Problems with data transmission in PROFIBUS networks can be attributed to

incorrect wiring or installation. These problems can often be solved using bus test

equipment such as bus monitors, which are able to detect many typical wiring errors

even before commissioning.

The list below helps to build up a RS485 network quick and accurate:

• Only use shielded and twisted-pair wiring as a RS485 bus line.

• Use a PROFIBUS bus connector plug to connect the RS485 bus segment.

• If the module is at the beginning or end of a bus segment, this connector must

have an activated bus terminal resistor combination.

• Ensure that the bus segment connected to the RS485 interface is terminated at

both ends.

• All PROFIBUS bus connector plugs in a network must be securely screwed

onto the RS485 interfaces.

• Attaching or removing the bus connector plugs, inadequately attached bus

connector plugs or loose bus wires within the plug can lead to malfunctions in

the networks.

• Attach or remove the RS485 bus connector plug quickly and without twisting

them.

The hardware units which form the AC 800M Controller are:

• Processor units (including base plates)

• Communication interfaces for different protocols (including base plates)

• Power supply units, providing various power output levels