Siemens SIMATIC S7-300 Series Reference Manual page 178

Glossary
Ground (to)
To ground means to connect an electrically conducting component to the
grounding electrode (one or more conducting components which have a very
good contact with the earth) across a grounding system.
Instance data block
A data block, which is generated automatically, is assigned to each function
block call in the STEP 7 user program. The values of the input, output and in/out
parameters are stored in the instance data block, together with the local block
data.
Interface, multipoint
³ MPI
Interrupt
³ The CPU operating system knows 10 different priority classes that control
user program processing. Belonging to these priority classes are, for example,
e.g. process interrupts. When an interrupt is triggered, the operating system
automatically calls an assigned organization block in which the user can program
the desired response (for example in an FB).
Interrupt, Delay
The Delay Interrupt belongs to on of the priority classes for SIMATIC S7 program
processing. It is generated on expiration of a time started in the user program. A
corresponding organization block is then executed.
Interrupt, diagnostic
³ Diagnostic Interrupt
Interrupt, Process
³Process interrupt
Interrupt, Watchdog
A watchdog interrupt is generated periodically by the CPU in configurable time
intervals. A corresponding ³ OB is then processed.
Glossary-8
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
A5E00111190-01