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PROFIBUS requires high availability since it is used as com- the process and group control level. The fast PROFIBUS DP is
munication system in process-oriented applications and as in- designed for applications in the decentralised programmable
strumentation and control medium between cells and objects. logic controller I/O.
However, PROFIBUS is highly susceptible to surges since high
inductive / capacitive coupling may occur due to its large spa- The latest development in the PROFIBUS segment is the intrin-
tial dimensions. sically safe PROFIBUS PA which can also be used in potentially
explosive atmospheres of process plants.
PROFIBUS is a product designation by Siemens for commu- A two-wire bus cable is typically used as a transmission me-
nication products (hardware and software) according to the dium. The physical properties of the bus system mainly comply
with the RS 485 standard.
standardised PROFIBUS standard (ProcessFieldBus). Alterna-
tive designations for PROFIBUS FMS and PROFIBUS DP are The bus devices can be connected as follows:
the Siemens product designations SINEC L2 and SINEC L2-DP.
While PROFIBUS FMS is only designed for data transmission ¨ Connection via 9-pin D-Sub miniature plug (typically
rates up to 500 kBit/s, PROFIBUS DP is capable of transmit- 3/8 pin assignment)
ting data with a transmission rate up to 12 MBits/s. PROFIBUS ¨ Connection via screw terminals
FMS (SINEC L2) is mainly used to handle large data volumes of ¨ Connection via bus terminals

1 – 3
bus devices

control room / cabinet
230/400 V
1 2 3
PROFIBUS
FMS or DP

Figure 9.13.1 PROFIBUS FMS or DP extending beyond a building with external lightning protection system

non-hazardous area hazardous area

230/400 V control room / cabinet

PROFIBUS PA

Figure 9.13.2 Intrinsically safe PROFIBUS PA in a building with external lightning protection system

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