SIMATIC TDC hardware
System Manual, 08/2017, A5E01114865-AL
75
CPU modules
4
4.1
CPU module CPU555
4.1.1
Areas of application
CPU555 is a graphically freely configurable processor module, enabling the implementation
of sophisticated highly dynamic control functions.
Use cases include:
●
Roll nip controls
●
Hydraulic positioning functions
●
Strip cooling systems
●
HVDCT control systems (high voltage DC transmission)
Note
Note the following for the CPU555:
•
CPU555 can only be used in the rack UR6021.
•
CPU555 can only be configured with a version V8.1 or higher of the D7-SYS automation
software.
•
The floating point unit used supports Floating Point data types, operations and exception
handling as defined in IEEE Standard 754 (2008). Floating point numbers are calculated
internally with 80 bits. This results in fewer rounding errors as compared to calculations
with only 64 bits (CPU551).
•
The CPU555 does not apply substitute values for invalid real values. This method
provides higher performance. Typically, invalid real values result from corrupted data
from external interfaces. Calculating with invalid real values can have unintended results.
Checking the input values with the CHK_R function block is recommended. With the
CHK_R function block, you can assign a substitute value for an error scenario.
Note
Note the following for operation with other CPUs:
•
Operation of the CPU555 together with a CPU551 is not approved.
•
Operation of the CPU555 together with a CPU550 is not approved.
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