There‘s a wide range of expansion modules to cover safety-related requirements. For example: monitoring emergency stop, safety gates, light curtains, two-hand controls and press safety valves, right through to motion monitoring functions. In particular, the safe analogue input modules Pnoz m EF 4AI cover tasks in the process engineering sector. With the Pilz analogue input module you can safely record and monitor any process operations up to SIL 3 of IEC 61511. The software tool of the configurable small controller, the Pnozmulti Configurator, provides software blocks for analogue input, feasibility, scaling and arithmetic functions for this purpose. They not only make project configuration simpler, but above all faster. Parameters for limit values and range monitoring can be set with just a few clicks.
Fast and precise reactions
The independent module program (mIQ) allows fine-granular settings for values, which can be processed quickly, directly within the module. Processes can also be monitored safely and with precision. Pressure, temperature, flow rate, distance, fill level or even rope speed and load are just some of the things that can be monitored reliably. Process cycles, which include force conditions, bending operations or distance measurement, are also included.
Users of the module program mIQ can also implement fast reaction times, as all the commands are processed decentrally within the module. During configuration, the analogue measured values can be scaled into numeric variables of any unit of measurement. Parameters for monitoring the limit value, range or work area can be set via the software tool. The design guarantees compliance with the sensors’ standard measuring range, so that established industrial standards are easy to apply.
Diagnostics firmly in view
The analogue input module provides the user with four independent, safe analogue current inputs of 4 to 20 mA with signed 15 Bit resolution. The measuring range is
0 tp 25 mA. The analogue inputs are suitable for connecting transducers or encoders with standardised current signals. Arithmetic functions such as averaging and calculating differential pressure make application easier and enable faster, more precise diagnostics. Up to six analogue values per module can be transferred to a fieldbus, so it is possible to intervene in the process more quickly, if necessary.
Analogue values can also be displayed and evaluated in combination with the visualisation software Pasvisu, also from Pilz. Fewer downtimes are the result, along with faster configuration and commissioning. Automation projects can be configured and visualised with Pnozmulti 2 in conjunction with the web-based visualisation software; the full function range can be used. Operators and service personnel obtain a comprehensive overview of the entire plant, including numerous diagnostic options, both locally and via remote access. As a result, faults or malfunctions can be detected and rectified quickly, plus downtimes are reduced.
Potential savings during configuration
In addition to the analogue modules, the software tool Pnozmulti Configurator also supports process industry users during configuration, documentation and commissioning. You simply need to select the necessary function blocks in order to establish the desired connections via drag & drop. The program then checks each action independently for plausibility. It also helps with the early detection of errors within projects: from Version 10.9, an offline simulation program in the Pnozmulti Configurator checks the completed project on the computer, before the newly created program is required to prove its functionality on the machine. The simulation program detects logic errors prior to commissioning. The actual procedure on the machine as it is running is effectively simulated – offline and without hardware, in the office so to speak.
Simple simulation
The logic connections are simulated and tested to avoid drop out and downtimes and to save time when the system is first deployed on the plant. The connection line between two function blocks may be forgotten in one section of the program. Practical example: an emergency stop pushbutton as an input controls an output in the configuration. Other functions, and therefore other lines, are planned in between them. If one line is forgotten, nothing happens later when the emergency stop is operated. So the simulation comes into play even during development. The opportunity for simulation means that users can guarantee that the configuration of the safety controller is “fault-free” and that the correct functioning of the program logic is verified before it is used live. Simulation helps users to maintain an overview of whether the configuration is correct, particularly when there are more than two or three safety functions on the machine.
Simple logic elements, counters and operating modes such as continuous cycle are calculated automatically as a first step. What’s more it’s even possible to simulate the entire application if elements that cannot be simulated are brought to the required state by forcing the outputs (fixed signal state is specified). Not every input needs to be defined. One special feature: in the Pilz simulation it is possible to specify a machine’s cycle time; there is an integrated time controller. Time sequences can be simulated: the seconds that an axis needs to move into position, for example.
Whether you have analogue modules for safe, precise process workflow management or software for simulation: user programs must remain clear and manageable, despite the expanding machine size and the increasing level of automation on the machine. Due to their function range, small controllers such as Pnozmulti 2 contribute towards safety while at the same time being easy to use.
Pilz GmbH & Co. KG, Ostfildern
Author: Andreas Volland
Product Manager,
Small Controllers
Pilz
