EtherCAT Technology Group: Working on new safety drive profile

EtherCAT permits open, vendor-independent configuration and control of safety functions in drives; Ethernet protocol makes stride in motion control.

By Control Engineering Staff January 19, 2009
Industrial Ethernet, related reading, links

Related reading
– Who Puts the‘Industrial’ in Ethernet?
– Product Research on industrial Ethernet protocols: Who’s leading?
– Other industrial Ethernet coverage
– New direction for industrial Ethernet cabling

Austin, TX EtherCAT Technology Group (ETG) is developing a new Safety Drive Profile to close the gap. With this upcoming drive profile, the safety functionality of EtherCAT drives with CiA402 (CANopen) or the SERCOS Drive Profile can be used and configured in a “manufacturer-independent” way. In a separate, earlier announcement, ETG cited significant EtherCAT progress in motion control. (See below.)
The IEC 61800-5-2 standard defines safety-relevant functions for drives. With these functions, safe stopping of the drive can be achieved, such as with Safe Torque Off (STO) or Safe Stop 2 (SS2), or safe monitoring of motion, such as Safe Limited Speed (SLS). With these features, dangerous movements at startup or during manual interaction with a machine can be avoided or limited in a safe manner.
To configure and control these internal drive safety functions in an open fashion, the ETG is now enhancing the Safety over EtherCAT protocol with a safety-related device profile for drives (Safety Drive Profile).
A bit of how it works
Based on the functions defined by IEC 61800-5-2, a control word is specified which enables the separate activation of these functions within the drive. Each function is represented by a bit in the control word. If a safety function is selected and operates within its boundaries, it is reported back to the supervision safety logic with a status word. All communication makes use of the underlying safety protocol. The definition of a uniform control and status word is said to allow the user to operate safety drives from different vendors in the same way with their safety controller. The variety of function blocks inside the controller is reduced and the operation is simplified, ETG says.
The configuration of the safety-relevant drive functions is also standardized within the profile. Typical implementations of the safety functions, which are defined by the IEC standard only in a very generic way, are considered and the corresponding parameters are described. Thus, an object dictionary is established and the user receives a uniform implementation and a vendor-independent understanding of the embedded functions within the drive.
EtherCAT Technology Group also intends to make the Safety Drive Profile available to other interested organizations and technologies since, by design, the profile is independent from the safety bus system being used. EtherCAT sets new standards for real-time performance and topology flexibility, while meeting or undercutting traditional fieldbus cost levels. An IEC and SEMI specification, EtherCAT features include high precision device synchronization, a cable redundancy option and a functional safety protocol (SIL3).
Motion control
EtherCAT Industrial Ethernet technology enjoys support from more than 40 servo drive vendors ETG says the support shows that “EtherCAT has taken a leading role in motion control: no other Industrial Ethernet technology is represented by such a variety of products from so many drives vendors.” the 2008 SPS/IPC/Drives show in Nuremberg, Germany, included aes include high precision device synchronization, a cable redundancy option and a functional safety protocol (SIL3), the group says. 
EtherCAT Technology Group (ETG) cites more than 850 members from 44 countries, claiming to be the
EtherCAT Technology Group
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