Trio's EtherCAT interface is a fully deterministic control interface based on standard 100base-T Ethernet hardware to servo drives and I/O devices. It can support up to 64 motion axes. EtherCAT replaces the traditional 10V analogue servo command and encoder feedback, or step/direction command signals to the drive electronics. The network was designed from the outset for real time motion and automation control and Trio support full cyclic, synchronous operation on all axes.
With EtherCAT, the Ethernet packet or frame is no longer received, then interpreted and copied as process data at every node. Rather, the EtherCAT slave devices read only the data addressed to them while the telegram passes through the device with negligible latency. Similarly, input/output data are inserted while the telegram passes through the slave. Advantages of EtherCAT include high-speed motion control, high update rates coupled with larger amounts of data transfer, reading and writing drive parameters and I/O and low installation cost using shielded Cat5 Ethernet cables.
CANopen over EtherCAT, also known as CoE, is the main protocol supported by the Motion Coordinators. Other protocols are supported for use with IO and some servodrives require a different protocol but they are in the minority.
The stepper motor interface is most recognized for its simplicity and ease of use. The typical stepper output signal from a Trio controller is a differential (5Vdc line driver) Step and Direction signal. Open collector (single-ended) is used on some legacy products but is limited in high speed performance and robustness in terms of noise immunity.
The Trio connection to the stepper motor-driver is ‘open loop’, although encoder position verification is common. All 4 Series controllers use the RS422 differential line driver interface.
The traditional ±10V analogue command signal is a very well known and common interface to servo drives and many other control devices. Trio controllers generate a 10V signal with either 12-bit or 16-bit resolution that represents velocity or torque command to a servo drive.
Position feedback is typically used, and some drives have a simulated encoder output to feedback to the Trio to close the loop. Trio’s proven 5 term position loop controller software updates the analogue output at the programmed servo period. (Settable between 125 usec and 2 msec update rate) With Trio, the 10V command output can be user controlled in an open loop fashion. Directly setting the voltage output can be used for a variety of control options such as a speed reference to vector and variable frequency drives.
CANopen is an internationally standardized higher-layer protocol for embedded control system running on CANbus. CANopen networks are used in a broad range of application fields such as machine control, medical devices, off-road and rail vehicles, maritime electronics, building automation as well as power generation.
Trio has a long history using CANopen for drive and I/O control. All Trio controllers have a built-in CANbus port for system I/O expansion to our modules. Trio has also in the past used CANopen for deterministic control or servo axes, however, faster and higher bandwidth networks such as EtherCAT have taken the lead. TrioBASIC provides commands for interfacing to many third party CANopen devices including remote I/O systems, pneumatic valve stacks, and high level messaging to servo drives.
A piezoelectric motor or piezo motor is a type of motor based upon the change in shape of a piezoelectric material when an electric field is applied to produce rotary or linear motion. Trio can use the 10V analogue command signal to control a piezo motor. These motors have unique control characteristics requiring specific features to accommodate. Trio has implemented parameters, such as output dead-band and offset, to allow control of piezo motors.
Ethernet-based control networks have prevailed as the technology of choice for motion controller to servo drive interfacing. RTEX (Realtime Express) is Panasonic’s propriety Ethernet network. It is deterministic running at 100Base-T and is designed specifically for real time motion and IO control.
Trio has an interface module for the MC464 Motion Coordinator to connect Panasonic RTEX drives. Advantages of RTEX are fast startup and close integration of service channel support tools.
Being an industry standard command signal, the +/-10V output from Trio can also command other devices such as pneumatic and hydraulic servo valves. These devices while under closed loop PID control offer very good performance of air and hydraulic controlled loads.
Position feedback can be incremental or absolute encoders, or analogue voltage. A servo axis in the Trio controller can be tuned to control such valves. Alternatively, for control of low bandwidth servo actuators, PID loops can be written at the application level for more flexibility.
Sercos is a high speed interface between the Motion Coordinator and one or more digital servo drives via fibre-optic link. The digital link allows the master to configure all the drive parameters, set the drives into run mode and close the position loop in real-time with a cycle period down to 250usecs.
The Sercos interface provides the flexibility of configuring multi-vendor control systems with plug and play interoperability. System designers are not limited to products from one manufacturer, but are free to choose those most suitable to solve their individual motion problems. The Sercos interface also reduces system cost, eliminates many types of noise problems and helps machine designers get motion control systems up and running quickly.
This special axis module provides a fully digital link to Control Techniques servo drives using the Control Techniques “Speed Loop Motor” SLM technology which gives a unique increase in servo loop performance over conventional analogue control loops.
Integrated support within Motion Perfect also allows for remote configuration of the drives and centralised distribution of drive parameters which gives fast maintenance turn-around in the event of a drive failure. The latest firmware supports “Position Loop Motor” PLM control which enhances the control loop accuracy and performance still further