Siemens SIMATIC S7-400 Hardware And Installation Manual page 287

System Function A system function block (SFB) is a function block integrated in the CPU
Block (SFB) operating system which can be called in the STEP 7 user program
when required, just like a function block (FB).
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 The time-delay interrupt belongs to one of the priority classes in
Interrupt 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 The time-of-day interrupt belongs to a priotity class in SIMATIC S7-400
Interrupt 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
Without galvanic connection to ground.
Ungrounded
User Memory The user memory contains logic blocks and data blocks of the user
program. The user memory can either be intergrated in the CPU or can
be plugged in on memory card or memory submodules. In general,
however, the user program is executed from the work memory (RAM)
of the CPU.
S7-400 and M7-400 Programmable Controllers, Installation Manual
C79000-G7076-C424-01
www.gkbpx.com
Glossary
Glossary-13