To stop users from disabling critical machine sequences, talk stirs occasionally to return to the use of proprietary control boards and code for safety reasons. But does a machine builder's role in designing a system that can't be defeated go beyond a defensible risk assessment and the accompanying due diligence?
"When using any software in a safety application, the machine builder must ensure the highest level of due diligence during the design and validation process," explains Juergen Bukowski, safety program manager, Sick (www.sickusa.com). "Consider the average PLC programmer or user whose job is to get the application running, but doesn't know or understand how to stop it safely. This is a recipe for disaster, since they are not typically involved in the safety concept or trained in failure-mode analysis. Keep safety as an external part of your automation project or process."
In the eyes of OSHA, the end user/owner of the machine is directly responsible for safety of the employees, explains Mike Garrick, product marketing lead specialist for interface, Phoenix Contact (www.phoenixcontact.com). "However, everyone also knows that the machine builder is in the most obvious path of civil litigation of an accident occurring during the use of the machine," he says. "The machine builder absolutely needs to make every effort to make a machine as safe as possible. A machine builder's reputation is important for success, and accidents will only subtract from how the company is perceived."
As part of the machine design, engineers need to help ensure safety while maximizing productivity during the initial setup and installation, operation, maintenance and decommissioning phases of the machine, says Tim Roback, marketing manager, safety systems, control and visualization, Rockwell Automation (www.rockwellautomation.com). "In addition, machine designers also must consider the domain of foreseeable misuse," he says. "This misuse can extend into programming changes to the control or safety system."
Multifunctional gate box MGB is designed to combine all necessary requirements to protect a safety door in accordance with EN ISO 13849 and EN 1088. The core of the modular system is the evaluation module, available with and without guard locking. Combined with a handle module and an optional escape release, MGB is designed to protect almost every safety door.
Diagnostics Add-On Instruction for CompactLogix and ControlLogix controllers, available as a free download, is designed to enable PLC programmers to retrieve detailed diagnostic data from an AS-Interface safety monitor and to be compatible with competitive AS-Interface Safety at Work safety monitors.
NE0A-SCPU01 safety network controller provides 12 safety inputs, two test outputs and six safety outputs, and can be used as a stand-alone controller, safety slave or DeviceNet standard slave. It has preconfigured and TÜV-certified program templates to select based on an application's safety requirements, potentially eliminating programming needs. Users can create safety circuits and save them as templates and reuse them on multiple NE0A units.
Omron Scientific Technologies
Interface and Intrinsic Safety Quick Reference Guide of the company's intrinsically safe products includes switching amplifiers, analog I/O, solenoid drivers, rotational speed monitors and relay and power supplies. The guide allows users to select the correct amplifier for a specific application and showcases unique, out-of-the-panel solutions for intrinsic safety.
E-Box for RAFIX 22 FS-type actuators has a yellow housing cap for e-stop buttons or a gray cap for push buttons or selector switches. E-Box is suited for installation on 40 mm profile rails. Contact modules are available with gold contacts for 35 V and 100 mA or silver contacts for 250 V and 4 A.
+49 751 891 307
|Don't Lose Your Head
HS5D compact interlock safety switches available with three contacts monitor if the head is separated or improperly mounted on the body. The switches are available with metal or plastic heads; the metal head can be rotated eight ways based on actuator entry, providing mounting flexibility.
L43S and L45S Compact GuardLogix programmable automation controllers (PACs) add diagnostics and information capabilities and single-programming environment previously available only in ControlLogix. GuardLogix PACs can control eight axes of integrated motion over SERCOS. Used in combination with Kinetix 6200 servo drives, users gain advanced safe-speed and safe-direction safety options.
E48 DIN-rail safety key interlock limit switch has its key portion affixed to the movable door, cover or other such guard, and the switch itself mounted to a rigid portion of the machine. When the guard is opened, the key is removed from the switch, positively breaking the normally closed contacts to interrupt the control circuit.
TwinSafe Terminals for EtherCat I/O are rated for SIL 3, conform to IEC 61508 and EN ISO 13849-1 PL e and are certified for North America. EL6900 safety PLC terminal can integrate 128 four-channel safety terminals (512 safety devices) and process 256 safety-relevant function blocks. A connection shutdown function permits interchangeable sections of equipment with safety terminals installed to be removed from the machine without causing safety system errors.
Safely Configure Safety
PSR-TriSafe safety controller monitors up to 20 safety input signals. Configuration uses SafeConf software with drag-and-drop interface to integrate new safety equipment. The software's simulation mode allows testing of the safety design without connecting the hardware. The software is available for free download.
757-662 and 753-667 Profisafe eight-channel modules integrate safety-related sensors into Sinumerik-840D Power line and Solution line. Via Profibus, 757-662 module (eight inputs) and 753-677 (four inputs/four outputs) support safety applications up to Cat. 4 PLe and SIL 3, as well as perform CNC control via Profibus couplers.
Safety Made Easy
SafeDesigner development and configuration tool provides integrated safety for programming safety-related functions in the Automation Studio development environment. Programming the safety application is reduced to virtual wiring of logical function blocks. The safety application created in SafeDesigner is processed in a safe controller—the SafeLogic —that supports cycle times starting at 1 ms and connection of up to 100 peripheral devices.
B&R Industrial Automation
|Safety Software Shares
Simatic WinAC RTX F software, preloaded on several PC-based or embedded controllers, controls critical devices from a standard dual-core Windows XP PC, eliminating a separate safety-rated controller. The software allows standard control logic and office applications to run on the same PC with safety-rated logic. The TUV-certified software complies with EN 954-1 to Cat. 4, IEC 62061 to SIL 3 and EN ISO 13849-1 to PL e safety standards.
XPSMC safety controller provides the same functionality as multiple safety relays and is an alternative to safety relays and safety PLCs. It reduces panel space and simplifies wiring and is available with either 16 or 32 inputs, and with eight safety outputs. All outputs can be converted into timed outputs. External communication is available via Modbus, CANopen or Profibus.
|From Many to One
SC22-3 safety controller manages multiple safety-related functions, replacing dedicated safety modules. It has 22 input terminals that monitor contact-based and PNP solid-state input devices, each input circuit is configurable to monitor an input signal or provide 24 Vdc sources and is configured using a PC or the module's built-in LCD display and buttons.
Universal Safety Controller Hub replaces multiple individual safety relay modules with one integrated safety center. The hub contains dry-contact safety relays and solid-state outputs. Safety channels A and B are pulsed independently and sequentially to protect from component and internal shorts of four-wire e-stop devices.
Model RS cable-operated safety-stop switches detect whenever the actuation cable is severed or pulled. The double-ended unit maintains constant tension on the pull cable. If the cable is pulled or the cable breaks, the handle rotates and activates the microswitch.
|Link Safety Systems
The Smart Safety Net links safety systems and safety relays in an easy and safe manner. By the use of the data bus technology, the time and effort for wiring is reduced considerably. It also makes it possible to build safety groups, so it is possible to turn off only one part of a facility to carry out maintenance. No IP address, special knowledge, special cable, special tools or IT expertise is required.
The PAC8000 SafetyNet has been approved by TÜV for applications requiring the handling of safety and process control data in the same controller. A 24 Vdc power supply extends the locations where SafetyNet systems can be implemented. The PAC8000 SafetyNet can handle safety and process control data in a single controller for SIL2 applications. PAC8000 SafetyNet offers static analyzer tools to identify all instances of the use of non-safety data in the safety controller.
GE Fanuc Intelligent Platforms
|PULSE INPUT MODULE
Triconex Trident safety system, version 2.1.1, has two new input modules to enable faster response to unsafe equipment conditions and to optimize trip data analysis to prevent future upsets. The system has an enhanced pulse-input module to measure speed, rate-of-speed change and rate of acceleration of rotating equipment in milliseconds. The digital input module monitors changes of state and sequence of events (SOE) and provides a timestamp resolution of 1 ms with an accuracy of 1 ms.
Invensys Operations Management
|Failsafe Alarm Module
The STA safety trip alarm accepts a signal input from transmitters, temperature sensors, resistance and potentiometer devices, and a wide range of other monitoring and control equipment. It provides three failsafe alarm outputs and is certified to IEC 61508: Parts 1, 2 and 3 by TÜV Rheinland for single use in safety instrumented systems up to SIL 2.
The ST4 series compact type 4 safety beam sensor offers a solution for machine guarding applications in which the installation of safety light curtains is cost-prohibitive or impossible due to space constraints. The sensors provide 0.1–15 m sensing range to cover narrow spaces to wide areas where light curtains are hard to install. The sensor head measures 14 mm x 31 mm x 28 mm.
Panasonic Electric Works of America
|Add the Safety You Need
FX3 Flexi Soft Modular safety controller expands module by module (12-144 inputs/outputs). Fast Shut-Off function increases response time, integration of EFI (Enhanced Functional Interface) and EtherNet/IP, Profibus-DP, Profinet, CANopen, Ethernet TCP/IP, and Modbus TCP reduces wiring and provides better diagnostics
The One Series line of digital pressure and temperature switches were recently evaluated by Exida Consulting for FMEDA and SIL Verification for plant safety applications needing faster response to initiate immediate and critical safety shutdowns. The switches never need calibration, have programmable adjustability and 0.1% repeatability.
United Electric Controls