Applications (General)
The SIMATIC S5-135U and S5-155U programmable controllers are multiprocessor controllers intended for automation tasks in the medium and upper performance levels. They provide a simple and economical solution for all automation tasks such as:

• Open-loop control
• Closed-loop control and computation
• Communication
• Operator control and process monitoring
• Signalling and logging
• Data processing
  
  The controllers are therefore suitable for:
• Machine control systems
• Process automation
• Process monitoring
• Co-ordinating functions

The standardized hardware technology, modular design of the PLCs and high performance capabilities of the programming device resultin the following features:

• Easy use thanks to simple assembly of the modules and connection to I/O modules Simple adaptability of the various process signals because of different input/output voltages of the I/O modules Analog process signals can also be adapted via I/O modules Extra-discrete modular assembly using different I/O modules Simple programming by structuring the program and using standardized program sections (function blocks) Off-loading of the central processors and user program through the use of intelligent I/O modules (e.g digital position decoder, valve control module) Simple communication with other programmable controllers and computers by means of internal communications processors and bus systems Easy system start-up by means of programming devices and service units with extensive programming and debugging aids The programming language used is STEP-5 with the following methods of representation: Control system flowchart - CSF Ladder diagram - LAD Statement list - STL and at a higher level GRAPH 5/II for sequential control