Siemens SIMATIC ET 200S Manual page 203

SYNC
SYNC is a control command of the DP master to a group of DP slaves.
By means of the SYNC control command, the DP master causes the DP slave to
freeze the current statuses of the outputs. For the following frames, the DP
slave stores the output data but the states of the outputs remain unchanged.
After each new SYNC control command, the DP slave sets the outputs that it
has saved as output data. The outputs are not cyclically updated again until the
DP master sends the UNSYNC control command.
System diagnostics
System diagnostics is the detection, evaluation and notification of errors that
occur within the automation system. Examples of such errors are program errors
or module failures. System errors can be indicated by means of LED displays or
in STEP 7.
System function
A system function (SFC) is a function integrated in the operating system of the
CPU that can be called up in the STEP 7 user program as required.
System memory
The system memory is integrated in the central module and designed as a RAM.
The system memory includes the address areas (for example timers, counters,
memory markers, etc.) as well as the data areas (e.g. communication buffers)
required internally by the operating system.
Times
Times are components of the ³ system memory of the CPU. The contents of
the "imer cells" are updated automatically by the operating system
asynchronously to the user program. STEP 7 instructions are used to define the
exact function of the timer cells (e.g. on-delay) and initiate their execution (e.g.
start).
Token
Access right on bus
Total current
Sum of the currents of all output channels of a digital output module.
ET 200S IM 151-7 CPU Interface Module
A5E00058783-04
Glossary
Glossary-11