Siemens CPU 313C Hardware And Installation Manual page 231

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Æ Interrupt, Time-of-day
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Bus access rights
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Data transfer rate (in bps)
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The SIMATIC system distinguishes between the Æ CPU operating system and
user programs. The latter are created with Æ 67(3  programming software, using
optional programming languages (LAD and STL). User programs are stored in
code blocks. data is stored in data blocks.
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User memory contains Æ code and Æ data blocks of the user program. The user
memory can be integrated in the CPU or can be provided on plug-in memory cards
or memory modules. However, user programs are always executed from Æ CPU
main memory.
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voltage-dependent resistor
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Æ Interrupt, Watchdog
S7-300 Automation Systems, Hardware and Installation: CPU 31xC and CPU 31x
A5E00105492-03
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13-15