Siemens SIMATIC NET Especificações descarregar pdf (Página 256)

246 Siemens Simatic S7 Driver Online Help

Process database block — individual units of instructions that receive, verify,

manipulate, and output process values. Process database blocks can also

compare a process value against an alarm limit and perform calculations based

on a specific process value.

SAC — the Scan, Alarm, and Control program (SAC) is a FIX/iFIX system task that

runs on a SCADA server. The primary task of SAC is to transmit and receive

data between the process database and the I/O driver’s common memory.

However, SAC also translates the data into the format expected by the process

database, examines the data against the alarm limits and generates alarm

messages, executes control logic, and detects exceptions.

Signal conditioning — the method by which a raw process data value is scaled.

Time-based scan time — a method of processing data that instructs SAC to retrieve

data at set time intervals. Use time-based scanning when your data changes

frequently.

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Siemens SIMATIC NET Especificações Página 256