Latest Safety Trend: Integrating Safety with Motion Control
While injuries due to industrial accidents have been dramatically reduced over the past decade – largely the result of rising awareness and investment in safety-instrumented automation – serious accidents still occur every day. Getting safety right is both a priority and an ongoing process. But safety systems have always been an additional and separate endeavor from basic control, adding cost and complexity to any application.
The latest evolution in safety systems involves the integration of safety with motion control functions and basic I/O. By combining these formerly separate functions on one device users realize key benefits including easier installation and implementation, reduced footprint and, ultimately, reduced cost.
The Simatic CPU 317TF-2DP controller from Alpharetta, GA-based Siemens Industry is a case in point. The new controller delivers basic motion control tasks with PLCopen-compatible motion control blocks and is suitable for coupled motion sequences of multiple axes. For safety-oriented applications, the controller meets the safety requirements of the relevant standards: EN 954-1 up to Cat. 4, IEC 62061 up to SIL 3, and EN ISO 13849-1 up to PL e.
The Step 7 option package S7-Technology provides programming and commissioning for all motion functions while fail-safe-specific applications are managed by another package, Distributed Safety, which comes with pre-configured, TÜV-certified library blocks, for key safety functions such as emergency stop, two-hand control, muting, and door monitoring.
Because the requirement for external safety hardware is eliminated, there is no longer a need for costly safety precautions at the machine, and thus less space is required in the control cabinet. Centralized and distributed fail-safe I/O and fail-safe drives according to PROFIsafe, the fail-safe communication standard, can be connected to the Simatic CPU 317TF-2DP. PROFIsafe drive safety functions, including Safe Torque Off (STO), Safe Stop 1 (SS1), Safe Brake Control (SBC), Safe Stop 2 (SS2), Safe Operating Stop (SOS), Safely Limited Speed (SLS), Safe Speed Monitor (SSM) can be used in addition to the familiar safety functions. PROFIsafe technology results in reduced wiring overhead, reduces the risk of errors when wiring, and increases flexibility during commissioning.
Food, pharma, material handling benefit
According to Siemens, this technology is particularly suited to common equipment applications such as palletizers, feeders, race tracks or flying shears, that often present a risk to workers that can generally only be ameliorated with secondary implementation projects.
From a vertical industry perspective, the following industries are likely to derive value from integrated safety and motion control.
- Food Processing – Highly modularized machines such as these have a large mix of automation and motion control that rely on network connectivity as a means of tying them together. By leveraging open standards (such as Siemens OPL and OPP) it is possible to take machines from multiple OEMs and standardize how they behave on the shop floor. Food processing OEMs are now able to bundle the elements of motion, PLC, and safety in one device and standardize communication, and machine functionality like state logic across the OEM equipment.
- Material Handling – Conveyors to multi-axis movers of material in the secondary or final packaging segment. In many cases these systems are left unguarded or have bulky point guards to protect them. The triple function controller + IO allow this to be done meeting the highest levels of safety without compromising the economic issues faced by OEMs trying to deliver a cost effective solution in a competitive environment.
- Pharmaceutical – S7 Platform along with HMI’s and higher level MES solutions provide one of the best solutions for handling requirements for the Pharmaceutical industry. CFR regulations are met though functionality in the S7 environment today and the enhancements as far as a single controller handling the machine control aid in areas such as change control and data logging.
Success factors of integrated safety and motion control include:
Improved uptime and standardization of control into a single controller. The need to troubleshoot multiple controllers is eliminated, and the programming environment is able to allow for predictive maintenance, energy savings, safety, and full machine control. In addition the micro memory card used in these devices allows for replacement without a large engineering effort. Swap the card, cycle power and go.
Simplicity and enhanced control. Because fewer components are required than is seen in traditional safety circuits, the engineering time required to develop and install them is reduced. Furthermore, integrated safety allows greater diagnostic capabilities not inherent in hardwired systems. The drive controller can send information of what safety function has been activated, and why, to an HMI screen for evaluation by the operator. The availability of such critical incident data reduces troubleshooting time.
Overall Impact – The impact to the OEM is in improving their bottom line. Profitability for end users results from increased uptime and better throughput. Profitability gains for OEMs and machine builders can also come from the reduction of hardware to achieve a similar or higher level of safety and motion control.
While these financial benefits are important to the operations that deploy them, Siemens representatives insist that integrating safety and motion control functionality delivers the most significant benefit in terms of reducing accidents on the shop floor. They believe that increased ease of deployment and a smaller footprint at the machine level will lead to increased deployment of safety systems in places that might not otherwise get them and that, they claim, should lead to fewer accidents.
To compete successfully you have to work faster and that means using technology that protects your workers and processes without having a major negative impact on operations. Combining critical functions like safety and motion control accomplishes this.
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