Operand Areas - Siemens SIMATIC S5-90U System Manual

Introduction to STEP 5
The STEP 5 programming language has the following three operation types.
• Basic
• Supplementary
• System
Table 7-1 provides further information on these operations.
Application
Methods of
representation
Special features
Refer to Chapter 8 for a description of all operations and programming examples.
7.1.2

Operand Areas

The STEP 5 programming language has the following operand areas.
I (inputs)
Q (outputs)
F (flags)
D (data)
T (timers)
C (counters)
P (peripherals)
K (constants)
OB, PB, SB,
FB, DB (blocks)
Refer to Appendix A for a listing of all operations and operands.
7-2
Table 7-1. Comparison of Operation Types
STEP 5 PROGRAMMING LANGUAGE
Basic Operations
In all blocks
STL, CSF, LAD
Interfaces from the process to the programmable controller
Interfaces from the programmable controller to the process
Memory for intermediate results of binary operations
Memory for intermediate results of digital operations
Memory for implementing timers
Memory for implementing counters
Interfaces from the process to the programmable controller
Defined numeric values
Program structuring aids
Supplementary
System Operations
Operations
Only in function
blocks
STL
For users with good
system knowledge
S5-90U/S5-95U
Only in function
blocks
STL
EWA 4NEB 812 6115-02b