Software Overview - Siemens SIMATIC S5-90U System Manual

System Description
PID Controller
Many applications require PID control functions in addition to the usual control tasks. For this
purpose, the operating system of the S5-95U has a PID controller which can be called up from the
program. The PID controller forms an integral part of the PLC's operating system and therefore
takes up no space in the user memory.
Standard Function Blocks
Besides the performance capabilities of a program, programming overheads are of great importance.
Standard function blocks including standardized program structures for recurrent, usually complex
functions can be loaded in the S5-95U. These software blocks can easily be linked into the program
and facilitate the task of programming considerably.

Software Overview

User memory (1 statement ˆ = 2 bytes)
Execution time for 1024 binary statements
Flags (512 retentive)
Counters (8 retentive)
Timers
Program organization:
• Structured programming
• Interrupt-driven program execution
• Time-controlled program execution
• PID controller
• Standard function blocks
In addition to process control, production processes often require supplementary functions, such as
closed-loop control or communication with I/Os. Special function modules are available for these
tasks.
Intelligent I/O Modules (IPs)
Intelligent I/O modules process open-loop and closed-loop control functions and positioning tasks
mainly autonomously. They can thus offload the CPU of the PLC.
Communications Processors (CPs)
Communications processors enable point-to-point connections between the PLC and printers,
peripherals or other computers via integral serial interfaces. They also permit interfacing with the
SINEC L1 LAN.
Operator Control and Process Monitoring Equipment (TDs, OPs)
Processes and functions in your plant can be visualized with the help of operator control and
process monitoring equipment especially tuned to SIMATIC S5 programmable controllers. Text
displays (TDs) can be used for process monitoring; operator panels (OPs) enable spontaneous
intervention in the process if necessary.
1-6
Table 1-4. Software Overview
S5-90U
4 KB
2 ms
1024
32
32
Yes
Yes
No
No
No
EWA 4NEB 812 6115-02b
S5-90U/S5-95U
S5-95U
16 KB
2 ms
2048
128
128
Yes
Yes
Yes
Yes
Yes