2. EtherCAT test and measurement from Gantner Instruments
EtherCat based technology for measuring and testing by Gantner Instruments supports EtherCAT in two different topologies. On the one hand, Gantner Instruments offers I/O modules as standalone EtherCAT slaves which is the most common EtherCAT structure of distributed, individual EtherCAT devices with a fixed I/O capacity. On the other hand, Gantner also provides the possibility to operate any amplifier cluster as a single EtherCAT slave. A secondary controller manages the single I/O modules and reports back to the EtherCAT master as a single slave. In this case, capacity depends on the cluster.
2.1 I/O Modules from Gantner Instruments as Standalone EtherCAT Slaves
In the following, I/O modules from Gantner Instruments featuring EtherCAT at module level are referred to as Q.bloxx EC. In the Q.bloxx EC Series, all module types of the classical Q.bloxx are available. Inputs for voltage, current, resistance, potentiometer, Pt100, Pt1000, thermocouple, measuring bridge, LVDT, IEPE, status, frequency, PWM and counter are provided – partly also for high voltage applications in electric vehicles and batteries with 1200V isolation voltage. Outputs for voltage, current, status, frequency and PWM are also given. The test and measurement characteristics follow the standard Q.bloxx system. More about Q.bloxx…
All Q.bloxx EC modules support the EtherCAT protocol according to IEC61158 and have a LVDS interface with a bus coupler. A single bus coupler may address up to 10 Q.bloxx EC modules. The bus coupler provides an additional port for configuration via USB. All Q.bloxx EC modules feature their own EtherCAT Slave Controller with Distributed Clock (DC).
In order to use the maximum sample rate of the Q.bloxx EC modules (up to 100 kS/S, device-dependent), Gantner supports the XFC technology (eXtreme Fast Control Technology). Up to 100 values may be transmitted per polling cycle. Respectively, the module records them equidistantly with a high sampling rate and transmits the data with the subsequent cycle. The oversampling factor may be varying from module to module. Thus, even different sampling rates may be realized in a single polling cycle.
Unlike traditional EtherCAT “terminals”, the Q.bloxx EC series also offers multi functional modules. These modules may be reprogrammed for different modes of operation – from voltage measuring device to thermocouple, resistor or bridge (etc.). Within these modes, subcategories may be given as for example resistance measuring with 2-, 3- or 4-wire technology. In addition, switchable measuring ranges, linearization and various filter functions (etc.) are available. The set-up is done alike classical EtherCAT slaves via SDOs. Unfortunately, a great variety of combinations of settings is possible. The traditional tools of the EtherCAT system configurations help users only with very little support for the configuration via SDOs. Therefore, Gantner Instruments delivers a configuration tool with a graphical user interface granting full access in cluding syntax check (etc.). This software makes the complete functionality of the Q.bloxx EC available easy and fast, preventing misentries at the same time. The configuration files may either be transmitted by the EtherCAT system configuration tool via FoE or directly via the bus coupler’s USB port to the Q.bloxx EC device.
The multi-functionality of the Q.bloxx EC series also affects the ESI (EtherCAT Slave Information) file. Hence each configuration requires a dedicated ESI file for a full set-up; the Q.bloxx EC modules provide a simplified ESI file. After initiation, the master may read the actual configuration (SDOs and PDO mapping) via CoE and go online. In case a master does not support this functionality, the configuration software of Gantner Instruments may also generate an individual ESI file with the according configuration.
2.2 Amplifier Cluster by Gantner Instruments as Single EtherCAT Slave
In a classical configuration, the decentralized devices from Gantner Instruments may be managed by a controller reporting back as a single device. The controller provides different interfaces for communication with your test bench environments, including EtherCAT. Also, each controller features an additional Ethernet interface. Both interfaces may be used independently. Process data for example may be, parallel to the test bench control signals, transmitted via EtherCAT at 1 kHz and additionally via Ethernet at 50 kHz for more demanding measurement tasks. The controller may also collect further data on predefined events, save data to a local storage device or send data via FTP (etc.). Thus, two or more applications are possible simultaneously with no cutback on EtherCAT functionality.
Gantner Instruments measuring devices provide full support for the EtherCAT standard. Depending on the application, the two concepts of the I/O modules, either standalone EtherCAT slave or as amplifier cluster reporting back as single EtherCAT slave, offer individual advantages. Both show the excellent accuracy and long term stability Gantner Instruments devices are known for alongside solid electrical isolation (even up to 1200 V), multi-functionality and flexibility. Leading manufacturers of test bench environments trust in Gantner Instruments.