Siemens S7-400 Installation Manual page 308

Glossary
System Memory
The system memory is integrated in the CPU and executed in the form of RAM.
The address areas (timers, counters, bit memory, etc.) and data areas required
internally by the operating system (for example, backup for communication) are
stored in the system memory.
T
Time-Delay Interrupt
The time-delay interrupt belongs to one of the priority classes in SIMATIC S7-400
program processing. It is generated after expiry of a time started in the user
program. A corresponding organization block is then executed.
Time-Of-Day Interrupt
The time-of-day interrupt belongs to a priotity class in SIMATIC S7-400 program
processing. It is generated depending on a certain date (or daily) and time of day
(for example, 9:50 or hourly, per minute). A corresponding organization block is
then executed.
Timer (T)
Timers are an area in the system memory of the CPU. The contents of these timers
are updated by the operating system asynchronously to the user program. You can
use STEP 7 instructions to define the exact function of the timer (for example,
on-delay timer) and start processing it (Start).
Total Current
Sum of currents of all output channels of a digital output module.
Transmission Rate
Speed of data transmission in bits per second
U
Ungrounded
Without galvanic connection to ground.
Glossary-16
S7-400 and M7-400 Programmable Controllers Hardware and Installation
A5E00069481-04