Optimum protection for man and machine
12 December 2018
MVK Metal Safety from Murrelektronik facilitates field bus solutions for safety technology.
Questions relating to safety are high-priority in the automation technology industry. The MVK Metal Safety fieldbus module, Murrelektronik’s industrial solution for technical safety installations, reaches the highest standards: Safety Integrity Level 3 (in acc. with IEC 61508 and IEC 62061) and Performance Level e (in acc. with EN ISO 13849-1). Two versions of MVK Metal Safety cover many different applications: one version with only inputs, and a mixed version with inputs as well as outputs.
In automation solutions with MVK Metal Safety, affected outputs are deactivated by targeted signals from the control unit. These kinds of applications require individual components to fulfill technical safety requirements to ensure that a safe control unit (F-PLC) can transmit safe signals, and also to assure the reliability of those transmissions.
The alternative to the F control unit
With the IP67 MVK Metal compact module, safe inputs/outputs can also be connected directly to the Siemens Sinumerik 840D SL Profinet CNC, used worldwide, provided that 'safety integrated' is enabled in the control unit. This enables safe data to be transmitted directly from sensors to control unit via the bus protocol. They no longer need to be wired passively in the control cabinet. This enables high safety standards (SIL3 and PLe) to be achieved.
The MVK Metal Safety fieldbus module from Murrelektronik can be equipped with only inputs, and also as a mixed module: with safe inputs as well as outputs. There are two inputs on each M12 input terminal. Depending on the application, these can be used for two single-channel or for one two-channel safety circuit. On two-channel applications, the channels can be configured to be equivalent or antivalent to one another. In addition, the discrepancy time is variable. This can be important factors if two sensors exhibit different response times and need to be set precisely to one another.
To enable data to be transmitted safety, MVK Metal Safety uses the PROFINET/PROFIsafe transmission protocol. Failsafe data are transmitted by PROFIsafe using the same bus line as non-safe signals. This enables the individual wires in a safe field bus solution to be integrated in standard modules without this imposing an unreasonable additional burden in terms of time and cost for engineering and installation specialists. This is the key to an enormous potential saving in terms of wiring. In addition, an existing field bus solution can be upgraded into a safe system without the need for major modifications.
Substantial increase in the number of safe outputs
Anyone creating an installation based on the Cube67 modular fieldbus system and is required to meet the highest of technical safety requirements will find a combination of the compact and safe MVK Metal Safety fieldbus module with Cube67-K3 modules to be the right solution. With safe outputs on the MVK Metal Safety – controlled by a PROFINET/PROFIsafe controller – up to twelve safe outputs can be created on the K3 module. These are distributed across two safety circuits, each with three double plug locations. It is therefore a simple matter to multiply the number of safe outputs. Because this makes it possible to dispense with safety relays, this saves space in the control cabinet and the minimisation of wiring reduces the resources involved in installation work.
Comprehensive diagnostic functionality
Given that the key to cost-effectiveness when installing machines and systems lies in reducing unscheduled periods of downtime, these highly developed diagnostic functions are a major plus point for MVK Metal Safety. All channels are monitored independently for faults such as overload, sensor short circuits or cable breaks. LEDs display the locations of faults precisely at the affected slots and reports these to the control unit. This ensures that individual channels of the system can be shut down precisely, without any adverse impact on adjacent channels that are not affected by faults.
In addition, the inputs on the modules are protected against crossfaults. Faults caused by crushed cables or shorts to ground are detected immediately and are reported precisely by channel. This indexing can be disabled when needed, e.g. when light curtains are used, and these can also be checked for crossfaults (i.e. for shorts across contacts).
Alongside versions with 7/8“ power connection and M12 connection for field bus lines, Murrelektronik provides a module with push-pull connection technology, suitable for defined areas of the automotive sector. The advantage of these is that the lines to the module can be plugged in by hand, without the need for tools.
Murrelektronik features a wide portfolio of EMERGENCY STOP and RESET buttons suitable for integration in technical safety applications. Just “Plug & Play” – they are easy to incorporate in the system. These control and monitoring devices can be connected via pre-configured M12 lines (with 4, 5, or 8 pins). A time-saving solution excluding the risk of wiring faults! The “Plug & Play” feature makes it possible to integrate command devices in machines and systems much faster. In particular the 42-millimetre versions can be installed remarkably quickly, simply by screwing on a metal clip to an aluminum profile, clipping in the housing and connecting up the M12 line. An accessory component can be used to connect a few versions of the EMERGENCY STOP button with lighting, or the RESET button, directly to the MVK Metal Safety fieldbus module. All components with an illuminated RESET button come with several colored inserts. It’s easy to attach these to the LED, thereby changing the colour.
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