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The ESX-3XM from Sensor-Technik Wiedemann (STW) is a robust, high-performance safety control unit, which can be programmed in C, Matlab and as a certified control unit also with Codesys Safety SIL2 in IEC61131.

Apart from the ESX-3XM (M stands for Medium), the ESX-3XL (L for Large) version is also available, which is more or less equivalent to double the ESX-3XM with regard to construction size and number of inputs / outputs.

Both control devices are suitable for safety-related applications up to Performance Level PL d or Safety Integrity Level SIL 2 and are based on a common architectural concept: In a robust aluminum die cast housing with automotive plug-in connector, a fast 32-bit microcontroller works with 6 MByte Flash and 4 MByte SRAM, four CAN-interfaces, one series interface, one buzzer and several LEDs.

Flexibility / scalability:

Apart from the flexible adaptation possibilities in the basic version – e.g. all inputs can be configured as current/voltage/digital or speed input using init-functions – the possibility to extend the device using so-called “Expansion boards” is the unique characteristic of the STW control device series:
On three (ESX-3XM) or six (ESX-3XL) slots, expansion boards with nearly unlimited additional functions cover a wide range of applications for your machine.
Currently, there are 14 expansion board versions with different inputs and outputs, additional RS232/RS485/CAN interfaces or even a programmable Linux system including Ethernet and USB available.
There is also the possibility to develop customer-specific expansion boards quickly and cost-effectively in order to fulfill highly customized requirements, e.g. for technical special solutions or to protect against product piracy.

Safety and diagnosability:

A second, independent processor monitors the different system voltages and the program sequence. If required, it switches off all outputs using a second switch-off path or resets the main controller.
Digital and analog feedback for nearly all signal paths allow a comprehensive diagnosis of the system including inputs and outputs.
In particular for safety-related applications, a safety layer API is available, which makes a separation of safe and non-safety (and non-interfering) application parts possible by means of a memory protection unit. This reduces the effort for re-certification in case of changes to the (non-safety) application software substantially.
The creation and maintenance of a safety-related application is possible comfortably using the safety manual and the diagnosis library.


The application software for the ESX series can be created very efficiently either in the standard language “C” or according to IEC 61131-3 (Codesys V3); a Matlab package is additionally available. Numerous comfort functions, such as current regulators & ramp functions for outputs or frequency determination for inputs are already integrated in the API. Various additional libraries, such as for example for CANopen, J1939 or error handling, simplify the system integration.
The clearly structured user manual and an inexpensive tool chain complete the comprehensive package.

Special features:

  • High computing power due to 32-bit TriCore processor with 32-bit floating point unit
  • High switching capacity of up to 135 A
  • Up to 136 I/Os possible; outputs for both ohmic and inductive loads
  • Programmable sensor voltage supplies
  • Communication via CAN, Ethernet, USB, LIN and series interfaces

Comprehensive software package with IDE, compiler and libraries for C or Codesys.