ABB Freelance 800F System communication System bus

System communication

System bus

The system bus interconnects the process stations,

operator stations and engineering station in the

Freelance 800F system.

The system bus complies with the Ethernet Standard

according to DIN/ISO 880 , Part  (IEEE 80 . ) and

can be used with twisted pair, fiber optic or coaxial

cable. It is also possible to use a combination of

these standards or to implement 100-MBit/s compo

nents within a network as high-speed backbone.

Freelance uses confirmed and unconfirmed services.

The unconfirmed UDP service is used for screen up

dating and lateral communication between controllers.

The confirmed TCP/IP service is used for alarming

and trend archiving.

The system bus has the following features:

• The ability to cover long distances

• A high data throughput

• Choice of various transmission media (such as

twisted pair, coaxial cable or fiber optics)

• A flexible network layout

• Easy connection to a higher plant management

level through the OPC standard

• Pre-programmed routines in the event of faults

• Good EMC properties

• Ability to switch bus members on and off during operation

• Highest availability through redundancy

Station bus (CAN bus)

When Freelance I/O racks are used, communication

takes place via the station bus. The station bus

complies with the CAN (Controller Area Network)

industrial standard.

The station bus has the following features:

• The ability to cover short to medium distances

• High data throughput, update times for signals

from  ms (binary) or 10 ms (analog)

• Exceptional degree of transmission safety and

interference immunity (Hamming distance = 6)

• Pre-programmed routines in the event of faults

• Good EMC properties

• Ability to switch bus members on and off during operation

• Automatic initialization of newly mounted modules

oPC

Freelance 800F provides an OPC gateway (server),

which allows OPC clients to access data and alarms

from the Freelance process stations. From Version

.1 upwards, the OPC server also allows access to

the DPV1 parameters and user parameters of

PROFIBUS and HART devices. In the case of HART

devices, this is only possible if they are connected

to a S900 unit. For V8. and higher, the parameters

of FOUNDATION Fieldbus devices can also be

accessed. It is possible to limit access to this data

at the OPC gateway such that an OPC client cannot

see certain process points and variables at all, can

only read other process points and variables, or has

both read and write access to certain

process points and variables.

The DigiVis operator station has a built-in OPC client,

which permits you to access data from external

OPC servers. Using this, for example, data from a

SIEMENS control unit can be integrated into a cus

tom graphic in DigiVis.

As several OPC gateways can be used in the Free

lance system, server redundancy can be established

using OPC clients that support this function. * The

Control Builder F engineering software supports this

with the redundant OPC gateway configuration.

The trend server option provides a special OPC

gateway that is used by the DigiVis operator stations

for user-defined trend displays. Access to the trend

server is fixed to “read only”, and all trend variables

are automatically available. There is one trend server

per Freelance system.

DMS-API

The DMS Application Programming Interface pro

vides C programmers with a Windows interface

through which they can access internal Freelance

communications services. This enables them to their

own Windows applications that can read online data

from the Freelance system and modify values.