Measure
The TwinCAT modules in the TwinCAT Power Collector of the Measure
group interact with EtherCAT power measurement terminals of the EL34xx series and handle both their configuration and the acquisition of measurement data.
The focus is on measuring the three phase voltages against neutral conductor and the three phase currents in a star connection.
CoE parameters are automatically set according to the module parameters via SDO communication. Measured values are read out via PDOs, variant handling and, if necessary, additional SDO communication. The recorded data is structured and made available for further processing in the system via defined Data Areas.
- PDO (Process Data Objects)
PDOs are used for fast, cyclic data exchange between the EtherCAT Terminal and the TwinCAT module. These transmit current measured values (e.g. current, voltage, power). - SDO (Service Data Objects)
SDOs enable acyclic access to parameters and internal process data of the EtherCAT Terminal. They are used to configure the EtherCAT Terminal (e.g. setting converter ratios) and to read out non-cyclic and extensive process data (e.g. harmonics), which should not be transmitted via PDOs due to their data volume or low update rate. - CoE (CANopen over EtherCAT)
CoE maps the communication between TwinCAT and the EtherCAT Terminal. It defines a standardized object dictionary that enables access to all parameters, states and data objects of the device via PDO and SDO. - Variant handling
The EL34x3 terminals support so-called variant handling. Different measured variables can be output via dedicated variant PDOs. The respective measured variable is selected via a multiplexing technique that uses selectors. This method allows the sequential reading of values (e.g. power components of the fundamental) that do not have to be transmitted cyclically.
PDOs ensure cyclic data exchange, while SDOs and variant handling are suitable for slower updated measured values and large amounts of data. Depending on the configuration and selection of process data, the modules use a combination of PDOs, SDOs and variant handling to record all process data. This ensures low utilization of cyclic communication via EtherCAT, while at the same time ensuring complete and timely acquisition of all measurement data.
The following is an overview of supported terminals and the corresponding modules:
Terminal | Module |
---|---|
EL3443 | |
EL3453 | |
EL3444 | TcPowerMeasureEL3444 (follows with version 0.1.1) |
EL3446 | TcPowerMeasureEL3446 (follows with version 0.1.1) |
… |
|
Further modules of the Measure
group for EtherCAT Terminals of the EL37x3 and ELM3xxx series can be found in the documentation for TF8350 | TwinCAT 3 Power Technologies.