Communication Between Units; Planning Redundant I/O Installation - Siemens SIMATIC TI505 User Manual

Communication Standard CATV taps and splitters combine I/O channels from the remote
between Units channel controllers (RCCs) to form two separate trunks (redundant I/O).
Each trunk leads to one of two RBCs located in a chassis that can house two
power supplies, although only one power supply is necessary. When the
active RCC transmits, the dual tap and splitter arrangement splits the
signal three ways:
When the active RBC transmits, the dual tap and splitter arrangement
splits the transmitted signal from either Trunk A or Trunk B two ways:
Each redundant RCC, RBC, or power supply can detect internal operating
faults. During normal operation, the RCC detects trunk faults and
recognizes the appearance or disappearance of redundant RBCs and power
supplies. When a fault is detected in the unit designated as active, the
corresponding backup unit automatically assumes control with minimal
process interruption and without operator intervention.
All input, output and SF message transactions occur between the active
RCC and the active RBC. The active RCC directs configuration messages to
both the active and stand-by RBCs, and the addressed RBC is responsible
for acknowledging the message. A "status request" command goes to the
active RBC to determine dual power supply status and to the stand-by RBC
to determine the condition of the stand-by transmitters. If the stand-by does
not respond to this request, the RCC directs the active RBC to command the
stand-by to assume a failed state. When communication problems develop
between the RCC and the active RBC, the RCC directs a "role swap"
command to the stand-by RBC.
Planning The SIMATIC TI560T /TI565T System Manual (PPX:560/565–8105–x)
Redundant I/O contains detailed instructions for installing remote I/O and for developing a
Installation power budget. The SIMATIC TI560/TI565 Hot Backup Installation Manual
(PPX:560/565–8103–x) provides details about the additional signal losses
with the Hot Backup Unit. Consult these manuals for installing the overall
I/O system.
NOTE: The x on the manual order number designates the manual edition.
SIMATIC TI505 Redundant I/O System User Manual
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To the stand-by RCC
To Trunk A
To Trunk B
To the stand-by RCC
To the active RCC
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