Siemens SIMATIC NET PROFIBUS Instrukcja Użytkownika Pobierz pdf (Strona 18)

18

PROFIBUS

Network components

Active RS 485 terminating element

The active RS 485 terminating element

terminates PROFIBUS, thus ensuring

a defined RS 485 signal level and

suppressing reflections on the line.

As operation is not dependent on field

devices, they can be decoupled from

the bus without feedback.

The power supply is not dependent on

the bus nodes.

Voltage is supplied to the terminating

resistor separately to the other I/O com-

ponents, either permanently or by volt-

age connected before the I/O devices.

Bus system termination enables the

stations (e.g. ET 200L/S) to be coupled

and decoupled at random, without

causing a malfunction.

Hardware Test Devices

BT200

During the installation phase,

the BT 200 test unit can be used to

check the PROFIBUS cable.

Installation errors can be detected

quickly and without any effort, no

special knowledge of PROFIBUS is

required.

Even before the plant is commissioned,

it is possible to test the RS 485 inter-

face of the PROFIBUS-DP slaves with

the BT 200. It is also possible to list the

accessible slaves on the wired-up bus

and this without a master on the PROFI-

BUS-DP.

Individual bus segments can be

function-tested in advance like this,

which reduces commissioning times.

In cases of faults, the latter two test

functions are useful for localizing the

fault and thus minimizing plant down-

times.

In future, the option will be available to

use a logger kit to save the test results

and print them out via a PC in the form

of a report.

In addition to German and English, the

BT 200 will also have available French,

Spanish, Italian and Portuguese.

Figure 35: Active RS 485 terminating

element

Figure 36: BT200 hardware test device

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