Siemens simatic c7-621 Hardware Installation Manual page 131

STEP 7 Programming software for creating user programs for SIMATIC 87
programmable controllers.
STEP 7 Tool
A STEP 7 tool is a tool of –> STEP 7 tailored to a specific task.
Substitute Value Substitute values are values that are output to the process or used in the user
program in place of a process value in the event of a fault occurring in signal
modules. The substitute values can be specified by the user (for example,
keep old value).
System
System diagnostics includes the detection, evaluation and signaling of faults
Diagnostics
occurring within the programmable controller. Examples of such faults
include program errors or module failures. System faults can be displayed via
LEDs or using the S7 Information tool.
System Memory The system memory is integrated on the CPU and implemented in the form
of a RAM. The address areas (for example, timers, counters, memory bits)
and the data areas required internally by the operating system (for example,
buffers for communications) are stored in the system memory.
T
Time-Delay The time-delay interrupt belongs to one of the priority classes in program
Interrupt execution on the C7 CPU. It is generated after expiry of a time started in the
user program. The associated organization block is then executed.
Time-of-Day
The time-of-day interrupt belongs to one of the priority classes in program
Interrupt
execution on the C7 CPU. It is generated dependent on a specific date (or
daily) and time (for example, 9:50 or hourly, or every minute). The
associated organization block is then executed.
Tool
Total Current
Sum of the currents of all output channels of a digital output module.
U
Ungrounded Without electrical connection to –> ground
C7-621 / C7-621 AS-i Control Systems
C79000-G7076-C621-01
STEP 7 tool
Glossary
Glossary-9