Functional Safety Controllers

ESx 3XLFunctional Safety Controllers from STW provide a fully integrated, highly flexible, SIL 2 certified software and hardware package for off-highway applications.

Mobile machines today have to fulfill a multitude of complex functions. In order to minimize risk, engineers need to incorporate safety-related conditions from EN13849 and IEC61508.The resulting increased complexity in the application software directly increases the development effort, since it must also be ensured that the non-safety software functions do not adversely affect the safety related functions. The IEC61508-3 describes methods to control the possibility of negative impacts on the safety and so minimize the certification effort for the non-safety software components.

STW is offering engineers a comprehensive functional safety control solution that is fully integrated, SIL2 certified but highly flexible.The development and maintenance of a safety-relevant software application is made possible thanks to memory protection mechanisms that clearly separate safety and non-safety functions.  STW’s safety solution is the first SIL2 certified package for CoDeSys V3.  A detailed safety manual clearly outlines the steps necessary to develop within the requirements of SIL2 and PLd.

In addition to the control unit ESX®-3XL (L for large), which is already used in many applications, STW has now added a little brother to the range, the ESX®-3XM (M for medium). Both control units are suitable for safety-relevant applications up to performance level PL d, or safety integrity level SIL 2, and share a common architectural concept: a fast 32-bit microcontroller with 6MB Flash and 4MB RAM, complete with 4 CAN interfaces, a serial interface, a buzzer, and multiple LEDs enclosed in a robust housing of die-cast aluminium with built-in automotive connectors.

The ESX®-3XM is roughly half the size of the ESX®-3XL and has half the number of inputs/outputs, which makes it ideal for smaller machines or for decentralised or distributed control system concepts in larger machines.

Besides the customization options that the base version offers – for instance, all inputs can be configured via init functions as current, voltage, digital or RPM inputs — the additional expansion board module concept is a unique feature of STW’s controller series: there are slots for up to three (ESX®-3XM) or six (ESX®-3XL) expansion boards with nearly unlimited additional functions.

There are currently 14 types of expansion boards in the range with various inputs and outputs, additional RS232/RS485/CAN interfaces or with Ethernet and USB. In addition, STW also develops customized expansion boards quickly and cost-effectively to meet exact requirements: e.g. for individual technical solutions or to protect against product piracy.

The application software for the ESX® series can be efficiently developed using the high-level programming language C or according to IEC 61131-3 (CODESYS V3). A Matlab package is also available. Various additional libraries such as for CANopen, J1939 or error handing simplify system integration.

The development and maintenance of a safety-relevant software application is made possible thanks to memory protection mechanisms and the safety manual. The clear user manual and inexpensive tool chain complete the package.

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