Physical bus characteristics
● The application protocols for PROFIBUS DP and PROFIBUS PA are defined according to
IEC 61158-2 and are identical for these two fieldbus variants.
– You can set the transmission speed on the PROFIBUS DP. The maximum transmission
speed with the Y-link is 12 Mbps.
– The transmission speed on the PROFIBUS PA is 31.25 Kbps.
● If the DP/PA coupler is connected directly on PROFIBUS DP, the transfer rate is set to
45.45 Kbps. The DP/PA coupler can be operated with SIMATIC S7 automation systems
and all DP masters that support the transmission rate of 45.45 Kbps.
● Depending on the power consumption of the PA devices, up to 31 PA devices can be
connected to the PROFIBUS PA.
Use in hazardous areas
● The intrinsically safe PROFIBUS DP is specified for the type of protection EEx(ib).
● The following components can be used in operating environments of the Ex zone:
– PA Link in Ex version, up to Ex Zone 2
– PA Link or FDC 157-0 DP/PA coupler in a housing that meets at least degree of
protection IP54; up to Ex Zone 2
– DP/PA coupler Ex [i] cannot be used for redundant configuration (coupler redundancy,
ring); up to Ex Zone 1
● If you use a SIMATIC AFDiS as a field barrier between the PA Link or DP/PA coupler and
the field devices, you can connect the field devices in hazardous areas of Zone 0 or Zone
1. The outputs of the SIMATIC AFDiS fulfill the requirements for types of protection EEx(ia)
and EEx(ib).
● The number of devices is limited by the current.
Additional information
● Section "Configuring a bus link for PROFIBUS PA (Page 147)"
● Section "High availability PROFIBUS PA (Page 83)"
● Section "How to configure the redundant PROFIBUS PA (Page 128)"
● Operating Instructions
DP/PA coupler, Active Field Distributor, PA Link and Y Link
4.3.5.5 High availability PROFIBUS PA
Functionality
PROFIBUS PA allows the connection of PA devices. A redundant PROFIBUS PA is connected
to FDC 157-0 redundant DP/PA couplers. If the communication path of the PROFIBUS PA
fails, the communication path is preserved as far as the spur line to the field devices.
High availability solutions in PCS 7
4.3 Solutions for communication
High Availability Process Control Systems (V9.0)
Function Manual, 05/2017, A5E39221836-AA 83
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