TWK-ELEKTRONIK GmbH Releases PR-110 CANopen Safety Encoder with SIL3 (TXSN)

By Chad Cox

Embedded Computing Design

June 14, 2022

News

TWK-ELEKTRONIK GmbH Releases PR-110 CANopen Safety Encoder with SIL3 (TXSN)
Image Provided by TWK

TWK takes the next step in sensor technology safety by introducing the new sensor model TxSN with magnetic sensor system in the series of functionally safe sensors with the established interface standard CANopen Safety (EN 50325-5). The TRSN multiturn encoder and its smaller singleturn brother TBSN are included in this model. It will be certified to meet the SIL3 level of EN ISO 61508 and is also ASIL-D compliant according to ISO 26262.

The SIL2/PLd safety level is insufficient for some applications. For example, autonomous vehicles, also known as AGVs (Automated Guided Vehicles), move autonomously and computer-controlled in public spaces. Because the safety requirements are particularly high here - serious personal injury and property damage can occur if the vehicle fails to function properly - the technology used must have a high level of safety.

To detect steering angle and speed, vehicles must be equipped with SIL3 components, sometimes on the wheels. Remote-controlled vehicles that move without the presence of a driver should also be mentioned. They are controlled remotely via a workstation. The operator can remotely steer a vehicle equipped with cameras and remote technology from his seat, which is outfitted with monitors, pedals, and a steering wheel. And, of course, back again. For transmission to the vehicle, fast internet according to the 5G standard is provided.

TWK provides SIL3 encoders for the remote steering station's control elements to record important control commands. The first TxSN devices will be delivered at the end of 2022. SIL3 capability is ensured by the fully redundant design and advanced diagnostic and watchdog functions.

Furthermore, extensive test procedures for hardware and firmware during the design phase and later for each device to be delivered in production are required for IEC 61508 certification with level SIL3 and ISO 26262 ASIL-D conformity. Each encoder then outputs the position value, which is recorded twice, verified, and processed separately.

Some features for future applications are planned for this model, as well as for the already established SIL2 / PLd models, to facilitate the design of the customer application. For example, a wide range of robust enclosures are available, including seawater-resistant aluminum as standard, various stainless steels - including food-grade, magnetically shielding stainless steel for applications with strong magnetic fields, and special enclosures for ATEX Zone 1 and 21 versions. The version with the smallest housing diameter (42 mm) is the most compact.

The TxSN also has position resolutions of up to 16 bits, parameterisable gate time for speed measurement, speeds of up to 10,000 rpm, and a variety of flange and shaft forms. Protection classes of up to IP69K are possible, as well as axial and radial shaft load capacities of up to 250 N. M12 plugs or cables are used to make the electrical connection.