PROFIBUS DP Network Characteristics

Overview

This section describes the characteristics of the PROFIBUS DP network over serial communication line. The PROFIBUS DP complies with the PROFIBUS DP protocol standard specification. For information on the specification and installation guidelines, refer to PROFIBUS Installation Guidelines published on www.profibus.com.

Standard Diagram

The simplified diagram of the PROFIBUS DP standard specification is as follows:

Characteristics for Connection to PROFIBUS DP RS 485 Bus

The RS 485 standard allows variants with characteristic like:

Polarization
Line terminator
Number of servers
Bus length

The RS 485 bus connection characteristics are as follows:

Characteristics	Value
Topology	Linear bus with line terminations
Transmission mode	Half duplex
Baud rate	Open style 4-terminal connector up to 1.5 Mbps Sub-D 9 connector up to 12 Mbps
Possible transmission media	Twisted-pair cable (standard version, type RS 485)
Maximum number of servers connected to one client	128 (0, 126, and 127 are reserved)
Maximum number of servers per derivation	32
Maximum number of repeaters per bus	Nine maximum repeaters including five maximum repeaters cascaded in one derivation
Line terminator	Active termination

Use of Repeaters

NOTICE
COMMUNICATION LOSS HAZARD Use a repeater to: Connect more than 32 PROFIBUS DP servers on the bus. Extend the bus cable length. Failure to follow these instructions can result in equipment damage.

A PROFIBUS DP network bus can be segmented with repeaters for many reasons:

Maximum length is reached when all the sub connection cable length is added in a segment.
To connect more than 32 PROFIBUS DP servers on the bus.
To isolate the derivation.
For derivation.
Connection to equipment.

For more information about the topology with a repeater, refer to the PROFIBUS Installation Guidelines.

Maximum Bus Cable Length

The bus cable length and corresponding baud rates are as follows:

Maximum bus cable length per segment	Maximum bus cable length with three repeaters	Baud rates
1,200 m (3,936 ft)	4,800 m (15,748 ft)	9.6/19.2/45.45/93.75 kbps
1,000 m (3,280 ft)	4,000 m (13,123 ft)	187.5 kbps
500 m (1,640 ft)	2,000 m (6,561 ft)	500 kbps
200 m (656 ft)	800 m (2,624 ft)	1.5 Mbps
100 m (328 ft)	400 m (1,312 ft)	3/6/12 Mbps