ABB PDP32.0 Manual - Page 8

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P D P 3 2 . 0 M A N U A L

Bus termination

Bus termination is required to prevent signal reflections from the bus cable ends. The PROFIBUS communication interface

PDP32.0 is not equipped with internal bus termination. Therefore, the PROFBUS D-SUB connectors at the first and last

PDP32.0 in a bus segment must have termination switched on.

In setups where the PDP32.0 is located in a drawer it is necessary to use an active bus termination at the end of the

PROFIBUS line. Use PDR31.0 in that case.

Further information on PROFIBUS wiring is available from the publication

PROFIBUS RS485-IS User and Installation Guideline from the PNO website.

Setting the bus address

The PROFIBUS module does not provide means to adjust the PROFIBUS address. The PROFIBUS address can be set in the

UMC and is copied over to the PROFIBUS module during initial connection between the UMC and PROFIBUS module. When

changing the address later on, perform a power cycle. See also the description "UMC100.3 - section 6: Configuring the

Fieldbus Communication".

Baudrate versus network length

When planning a PROFIBUS network, the following rules must be considered.

For the whole network, i.e. starting at the DP Master up to the last DP Slave:

• approx. 4 up to 8 DP segments by Repeater (see data sheets of the Repeater)

• the slowest DP subscriber sets the transfer rate of the DP line

• number of PROFIBUS DP subscribers ≤ 126 (Addresses 0 ...125)

For a segment:

• number of DP subscriber ≤ 32 (subscriber = device with / without PROFIBUS address)

• bus termination each at the beginning and the end of every DP segment necessary!

• trunk cable length (LT) see diagram (length depending on transfer rate)

1200

1000

400

200

100

The maximum transmission distance that can be achieved using copper cables is

directly related to the transmission speed chosen for the PROFIBUS network. As

a result, these two variables must always be considered together.

Transmission Speed