Siemens Simatic S7-400 - Manual (Page 615)

Glossary
Glossary-9
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
Interrupt, diagnostic
³
Diagnostic Interrupt
Interrupt, end-of-scan-cycle
³
Hardwareinterrupt
Interrupt, hardware
³ Hardware interrupt
Interrupt response time
The interrupt response time is the time from when an interrupt signal first occurs
to calling the first instruction in the interrupt OB. The following general rule
applies: Higher priority interrupts take precedence. This means that the interrupt
response time is increased by the program processing time of the higher priority
interrupt OBs and interrupt OBs with the same priority that have not yet been
processed (queue).
I/O bus
This is part of the
³
backplane bus in the programmable controller, optimized for
the rapid exchange of signals between the CPU(s) and the signal modules.
User data (for example, digital input signals of a signal module) and system data
(for example, default parameter data records of a signal module) are transferred
via the I/O bus.
Isolated
With optically isolated input/output modules, the reference potentials of the
control and load circuit are galvanically isolated (by an optocoupler, contact
assembly or repeater, for example). Input/output circuits can be connected to
common potential.
Keep last value (KLV)
The module retains the last value read out before STOP mode.
Load memory
The load memory is part of a programmable module (CPU, CP). It contains
objects generated by the programming device (load objects). It is implemented
either as a plug-in memory card or a permanently integrated memory. In the case
of SIMATIC M7, the load memory can also be defined as a directory on the hard
disk.