Rapid measurement data acquisition for industrial applications
The requirements for production automation are constantly increasing. High quality requirements, together with short cycle times mean that, amongst other things, automation solutions must also process an increasingly greater number of measurement values ever more rapidly. In order to reduce the load on the central controller in such cases, solutions with so-called decentralized intelligence are increasingly being used - including in the sector of industrial measurement technology.
In order to meet these requirements for industrial measured data acquisition, the measurement technology specialist HBM has introduced their PMX system to the market. Measurement data acquisition, further processing of the data and transmission to a higher-level controller are all implemented here at very high speeds. For example, sampling rates of up to 19.2 kHz are possible. At the same time, very high precision of the measured data is guaranteed through measuring amplifiers with a high 24 Bit resolution.
Communication with the automation environment
The system comprises a basic device that holds up to five plug-in cards. The first slot is reserved for a communication card that enables integration within a higher-level automation system. The other four slots are then available for amplifiers with four channels each and combination input/output cards. Currently, three different modules with measuring amplifiers are available for strain gauges (SGs), for analog inputs and outputs, and for digital outputs. This allows the most frequently required physical quantities to be measured, e.g. force, torque, pressure, strain, temperature, etc. All modules are supplied with voltage via the basic device. Communication with a PC or operating unit used for configuration or visualization is implemented via Fast Ethernet. In addition, the basic device is equipped with a USB interface which can be used, for example, to save configurations on a USB stick and read them back in again (device backup). The connection of peripheral units, such as hard drives or barcode scanners, can also be used to save quality data and to include component identifications in these data.
Measurement technology in industrial applications must integrate seamlessly in the communication protocols of the automation systems. As data volumes and speed requirements have grown over the past years, Industrial Ethernet has become increasingly popular as a communication protocol in automation technology. This is why the PMX system supports the real time Ethernet protocols Ethercat and Profinet which can also rapidly transmit large data volumes. The measured signals can already be processed internally by the amplifier and evaluated in real time. The PMX system can therefore directly implement some of the tasks in the amplifier that would otherwise be taken over by the higher-level controller. These include, for instance, mean value determination, peak value acquisition and other mathematical calculations, as well as PID controllers. In addition to the maximum 16 measurement channels that such a PMX system offers, the user also has up to 32 so-called virtual calculation channels available. The system has powerful signal processors for this purpose which can implement the calculations at the required speed. PMX ensures that all signals can meet the hard real time conditions with this real time core. All measured values and the derived values calculated in the virtual calculation channels can be transmitted in real time with up to 10 kHz via Ethernet to the controller of the machines and plants. This decentralized measurement technology intelligence is particularly important, especially for applications with a very high degree of automation, in order to reduce failure frequency and the system load on the controller.
Typical applications for such decentral measurement systems, which can assume some of the control tasks, are found in production, for instance the monitoring of presses. These range from tablet and powder presses, right up to sheet metal presses as used in the automotive industry. Such systems can also be used in the sector of assembly and joining monitoring. Important machine parameters must frequently be monitored in large and complex machines and plants. This so-called condition monitoring contributes to minimizing standstill times and therefore reducing costs incurred by production downtimes. Another classic application case for measurement systems such as the PMX is the industrial test bench setup, where complex components are tested for their maximum loading capacity and practicality. Industrial Ethernet has also come to the fore as a communication medium in this sector over the past years. The same applies for quality test benches that check the quality of finished products as end-of-line test benches. The storage of the quality data acquired here in a database also poses increased requirements for the communication architecture of the measurement technology systems.
To Sum it up
High sampling rates, rapid data transmission and integrated intelligence (digital signal processors DSP and CPU) for relieving the higher-level automation solution are significant requirements facing the measurement technology systems that are used in the modern industrial environment. Communication via real time-capable Industrial Ethernet protocols with high data transmission volumes is also playing an increasingly greater role. The measurement technology specialist is now introducing a system to the market with PMX, one that meets all these requirements and is therefore suitable for diverse tasks in industrial measurement technology.