Medium complexity
February 1st 2004 Pilz Automation Technology has launched the PNOZmulti, a cost-effective software-configurable safety controller for all safety functions in applications up to BS EN 954-1 Category 4. This is designed for medium-complexity machinery for which conventional electromechanical relays or microprocessor-based electronic safety relays are unsuitable, and where the use of programmable safety systems would be excessive.
The PNOZmulti is as simple to use as traditional PNOZ electromechanical relays, with drag-and-drop configuration software that needs no specialist programming skills. Furthermore, the modular nature of the controller means that the customer only has to purchase and install the required functionality, thereby saving both costs and cabinet space. Using the modules already available, customers can employ a PNOZmulti controller for safety-related control systems with emergency stop switches, gate switches, limit switches, light curtains, safety mats and two-handed starts.
In operation, the PNOZmulti provides full diagnostics, either by using the multicoloured LEDs on the front of the unit or via a communications port that transmits diagnostic log files to the configuration software. Should the safety system need to be upgraded or modified, it is easily reconfigured in software or the controller can be completely reused on a replacement machine. Being entirely electronic, with no moving or wearing parts, means that the PNOZmulti is exceptionally reliable and long-lived, even in areas where shock or vibration cause difficulties for traditional electromechanical relays.
For many applications, the PNOZ m1p base unit alone is sufficient. This has 20 freely configurable inputs, four test pulse outputs, one auxiliary output, four safe semiconductor outputs (or two for Category 4 applications) and two safe relay outputs (or one for Category 4 applications). However, for more complex safety related control systems, customers can add up to eight of the available expansion modules. These are the PNOZ mi1p eight-input module, the PNOZ mo1p with two safe semiconductor outputs, the PNOZ mo2p with one safe relay output (or this can be used to provide two auxiliary outputs), and the PNOZ mc1p communications module that has 16 auxiliary semiconductor outputs. Each additional module is simply plugged into the adjacent module, with no need for wiring and, therefore, no risk of wiring errors being made.
Configuration is performed entirely in software, which can take place before any hardware has been purchased, thereby helping cashflow for machine builders. Using the PNOZmulti Configurator software is very straightforward: first, the user defines the inputs and outputs, then the logic functions are specified and, finally, the links are made between the inputs, outputs and logic operators. Counters show the amount of chip card memory used as well as the number of logic elements used. Comprehensive help files and application examples are provided, though the drag-and-drop software is intuitive.
In addition, the configuration package can also be used to visualise the operation of the logic circuit by highlighting the active elements and links. This visualisation and diagnostic facility benefits both circuit designers and commissioning engineers.
One of the most important aspects of the design of safety related control systems, namely documentation, is largely automated within the configuration tool, which saves considerable time and effort for users and those assigned the task of checking and approving the designs. When the configuration has been programmed and approved, it can be downloaded to the PNOZmulti hardware by using a Smartcard (the same technology as a mobile telephone SIM card). Smartcards can be quickly and securely written to using a reader/writer attached to a PC, then the Smartcard is installed in the PNOZmulti base unit. Alternatively, the Smartcard may be written to while installed by linking the PC to the PNOZmulti base unit with a standard RS232 serial cable. Should modifications to the safety controllers configuration ever be required, these can be made by reprogramming the Smartcard.
The facility for writing Smartcards is useful where series machines are being built. In this case, the configuration need only be carried out once in
software, then multiple Smartcards produced. Smartcards and a Smartcard reader are included in the PNOZmulti Toolkit, that also contains the
Configurator software, cables and manuals. More Smartcards may be ordered separately. More articles from Pilz Automation Technology: | 
