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EtherCAT communications added to Downstream Pressure Control Valves

EtherCAT communications added to Downstream Pressure Control Valves

EtherCAT is, to the Semiconductor Industry, an emerging communications network that enables very fast and synchronous addressing and control of a large number of devices on a network.

It is envisioned by some system makers that most or all functional sub-modules on a processing system (ex. throttle valves, mass flow controllers, RF matching networks, gauges, switches, etc…) can be controlled synchronously from one central command point. Imagine the possibilities!
The throttle valve, for example, can begin making a position adjustment before the pressure spike occurs as a result of changing a gas flow-rate so as to smooth out a critical process control parameter. Or, every substrate processed is exposed to exactly the same set of chemical concentrations, plasma power levels and pressures because each and every aspect as such is centrally controlled and broken down to micro-second long increments of data exchange.
Regardless to which extent the EtherCAT capabilities are used on wafer processing tools, Nor-Cal stands ready to help the system integrators with its EtherCAT enabled QPMseries controller – part of the Company’s IntellisysTM IQ+ control technology.
A brief, yet informative, summary of the EtherCAT technology follows, the information is extracted from the EtherCAT Technology Group (or ETG) website where more information can be found at www.ethercat.org.

For questions or comments about Nor-Cal’s EtherCAT product availability, please contact us at sales@nor-cal.eu and ask for EtherCAT product support.

  • EtherCAT

Synonymous with speed, performance and simplicity, it is an open real-time Ethernet network originally developed by Beckhoff Automation.
The EtherCAT technology overcomes the system limitations of other Ethernet solutions.
With EtherCAT, the Ethernet frame is processed on the fly; the newly developed FMMU (fieldbus memory management unit) in each slave node reads the data addressed to it, while the telegram is forwarded to the next device.
Similarly, input data is inserted while the telegram passes through.
The telegrams are only delayed by a few nanoseconds.
On the master side, inexpensive and commercially available standard network interface cards (NIC) or any on board Ethernet controller can be as hardware interface.
The common feature of these interfaces is data transfer to the PC via DMA (direct memory access), i.e. no CPU capacity is taken up for the network access.

  • Protocol

The EtherCAT protocol uses an officially assigned EtherType inside the Ethernet Frame. The use of this EtherType allows transport of control data directly within the Ethernet frame without redefining the standard Ethernet frame. Addressing of the Ethernet terminals can be in any order because the data sequence is independent of the physical order. Broadcast, Multicast and communication between slaves are possible.

  • Performance

EtherCAT reaches new dimensions in network performance. Thanks to FMMU in the slave nodes and DMA access to the network card in the master, the complete protocol processing takes place within hardware and is thus independent of the run-time of protocol stacks, CPU performance or software implementation. The update time for 1000 distributed I/O’s is only 30 μs. Alternatively, the communication with 100 servo axes only takes 100 μs. During this time, all axes are provided with set values and control data and report their actual position and status. The distributed clock technique enables the axes to be synchronized with a deviation of significantly less than 1 microsecond. The extremely high performance of the EtherCAT technology enables control concepts that could not be realized with classic fieldbus systems. For example, the Ethernet system can now not only deal with velocity control, but also with the current control of distributed drives. The tremendous bandwidth enables status information to be transferred with each data item.

  • Topology

Line, tree or star: EtherCAT supports almost any topology. The bus or line structure known from the fieldbusses thus also becomes available for Ethernet. Particularly useful for system wiring is the combination of line and branches or stubs: The required interfaces exist on the couplers; no additional switches are required. Naturally, the classic switch-based Ethernet star topology can also be used. Wiring flexibility is further maximized through the choice of different cables, including inexpensive standard Ethernet patch cables or plastic optical fiber (POF) in combination with switches and media converters.

  • Distributed Clock

Accurate synchronization is particularly important in cases where widely distributed processes require simultaneous actions. This may be the case, for example, in applications where several servo axes carry out coordinated movements simultaneously.

  • Hot Connect

The Hot Connect function enables parts of the network to be linked and decoupled or reconfigured “on the fly”. Many applications require a change in I/O configuration during operation. The protocol structure of the EtherCAT system takes account of these changing configurations automatically.

  • Openness

The EtherCAT technology is fully Ethernet- compatible and truly open. The protocol tolerates other Ethernet-based services and protocols on the same physical network - usually even with minimum loss of performance. There is no restriction on the type of Ethernet device that can be connected within the EtherCAT segment via a hub terminal.