Technical data

Topologies of SIMATIC NET PROFIBUS networks
2.4 Topologies with PROFIBUS PA
PROFIBUS Network Manual
38 System Manual, Edition 04/2009, C79000-G8976-C124-03
Design
The total current of all the field devices must not exceed the maximum current of the DP/PA
coupler. The maximum output power therefore limits the number of field devices that can be
connected to PROFIBUS PA.
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Field device
1
Field device
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Field device
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Field device
2
Explosionprotected area
Field device
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PROFIBUS-PA
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Figure 2-10 Remote power supply for field devices in the hazardous and nonhazardous area
Expansion
If the maximum output current of the DP/PA coupler is exceeded, you will need to include a
further DP/PA coupler.
Total cable length
The total cable length is the sum of the main cable and all the spur lines.
With a standard PROFIBUS PA cable with a cross-section of 0.8 mm², the maximum length
of the cable in total is
● 470 m (with the full configuration at the cable end) up to 1900 m
for DP/PA coupler (6ES7 157-0AC83-0XA0)
● 920 m to 1000 m for DP/PA coupler Ex [ia] (6ES7 157-0AD82-0XA0)