SIMATIC S5 - S5-90u controller


We present an overview of the hardware and software features of commonly used programmable logic controllers from the renowned Siemens company in industrial equipment automation. The SIMATIC S5 system is used at different levels of automation and in various industries.

The S5-90U controllers supplied by Siemens. enable small two-state control tasks such as controlling sluices, pumps, compressors, and building automation systems. Equipped with suitable analogue modules, they can also control process operations and equipment such as packers, automatic washers, heating systems, air-conditioning systems, ventilation systems, transport systems and automated greenhouses. The S5-90U controllers feature a compact design for easy mounting on a standard 35mm profile rail. The connection of the signal lines is made directly to the controller terminals located in the housing. As requirements increase, the controllers can be expanded using the S5-100U system field modules. Using the special IM 90 interface module, up to 6 S5-100U system field modules can be connected to a single S5-90U controller.

The S5-90U controller has a V24/TTY 20mA serial interface as standard, which allows connection of an operator panel, programmer or PC. This interface also allows operation on the SI NEC L1 network (SLAVE). Power supply is provided by a built-in power supply unit, which allows the use of 220V AC mains power and provides 24V DC auxiliary voltage.

The S5-90U controller processor allows 1KB of instructions to be processed in approximately 2ms. The programmer can use 4KB of RAM or EPROM/EEPROM memory modules. The controller has 1024 markers (FLAG), including 512 with battery backup, 32 timers in the range 0.01...9990s and 32 counters in the range 0...999, 8 of which have battery backup. The controller's central unit allows the use of logical operations, arithmetic operations, timer functions, pulse counting, data exchange and other operations.

The S5-90U controller has 10 galvanically isolated binary inputs, eight of which are standard 24V DC inputs and two additional ones can act as alarm or high-speed (1kHz) counter inputs. The controller's outputs are 6 standard relay outputs. The S5-90U controllers can be expanded to 208 binary inputs/outputs, 16 analogue inputs/outputs and 13 external counters.

The integration of intelligent field controllers, such as PID controllers, positioning modules and communication modules, allows the functionality of the controllers to be extended. It is also possible to connect the S5-90U controllers as SLAVEs to larger SIMATIC S5 controllers, such as the S5-115U, S5-135U or S5-155U, in combination with the SINEC L1 network.

It is worth noting that the standard serial interface connector and the possibility of exchanging information via the SINEC L1 network make it possible to connect a variety of devices for process visualisation and parameterisation. The available diagnostic functions of the STEP-5 software enable the graphical presentation of the current connection result and the tracking of selected inputs, outputs, tags (FLAGs) and variables.

In summary, the S5-90U controllers offer a high level of reliability and advanced features, making them ideal for industrial automation applications.

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Author of entries
Tomasz Gilewski

Hello, my name is Tomasz Gilewski. I am the author of books on the S7-1200 controller and HMI panels (i.e. Siemens hardware). I have been programming exclusively on Siemens hardware and engineering tools for several years.

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