Siemens SIMATIC ET 200AL, System Manual

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Description
2.2 Structure of PROFIBUS networks
PROFIBUS with STEP 7 V13
Function Manual, 12/2014, A5E03775446-AC
29
2.2.3 Active network components
2.2.3.1 Network components in electrical networks
Active network components
The following active network components are available for PROFIBUS in electrical networks:
●
Repeater RS485
● Diagnostics repeater
● PROFIBUS Terminator
● DP/DP coupler
● IE/PB Link PN IO
● IWLAN/PB Link PN IO
● Active components for the connection of CAN
● Active components for the gateway between PROFIBUS and AS-Interface
–
DP/AS-i LINK Advanced
– DP/AS-Interface Link 20E
– DP/AS-i F-Link
RS485 repeater
The RS485 IP20 repeater connects two PROFIBUS bus segments in RS485 technology with
up to 32 devices. It provides transmission rates from 9.6 kbps to 12 Mbps.
The RS485 repeater refreshes a signal regarding amplitude, signal width and edge
steepness between two segments. It is used when more than 32 stations are connected to
the bus or the maximum cable length of a segment is exceeded.
Bus segments can be operated ungrounded (galvanic isolation of segments) with an RS485
repeater.
Diagnostics repeater
The diagnostic repeater connects three PROFIBUS segments in RS485 technology, two of
which are diagnostics-capable segments with 31 devices each. It is designed as DP slave to
send diagnostics alarms to the DP master.
The diagnostic function provides the location and the cause of cable faults, such as wire
break or missing terminating resistors. The fault location is indicated relative to the existing
devices.
The diagnostics repeater refreshes a signal regarding amplitude, signal width and edge
steepness between the segments. The cascading depth between any two PROFIBUS
devices is limited to nine diagnostics repeaters.