By Richard R.T. Tatham

The Paul Scherrer Institute (PSI) in Switzerland, in close collaboration with interested groups from the Swiss universities and the Swiss Federal Institutes of Technology, is building an advanced synchrotron light source in Switzerland (Figure 1) scheduled for operation this year. The facility has been named the Swiss Light Source (SLS). As part of this program, instrumentation is required to monitor the large quantity of data generated.

Hytec Electronics Ltd., which has been supplying the hardware and software building blocks for creating advanced data acquisition and control systems for over twenty years, is playing a significant role in the SSL project. Specializing in modular instrumentation to international standards, Hytec products include VME, CAMAC, CANbus PCI, BitBus, and the recently introduced VME64x, with IndustryPack plug-in cards.

Limitations of VME32
In some applications, VME32 has shown limitations, summarized as follows:

  • Noisy: It is a processor, namely, the Motorola 68030 bus.
  • Limited I/O: There are often not enough I/O lines to get to rear-mounted transition cards. As a result, connectors are put on the front panel allowing no flexibility in terms of signal levels, conditioning, and so on.
  • No Hot Swap: There is no concept of hot swap. If a card fails, the device must be switched off and on, and then must be rebooted.
  • Manual Setup: Cards have to be set up manually, which can be complicated and requires technical skills.
VME64
The arrival in the early 1990s of VME64 permitted 64-bit data handling, doubling the throughput and providing a range of new features that transformed the VME to a '90s bus. Further significant enhancements for the new millennium came with the introduction of VME64x (VME Extensions), which satisfied the demand for more flexible I/O capability, rugged mechanics with EMC/ESD protection, and larger address capability. Additionally, the features of VME64x made it easier to use with geographical addressing and hot swap. A typical VME64x module is shown in Figure 2.

At the Swiss Light Source, 145 crates are being used for the control and data acquisition of radio frequency, diagnostics, vacuum, power supply, and beam lines. With such a large number of systems, crates must have a high reliability and low down time when adding or replacing a module.


Thus, the Paul Scherrer Institute chose to use VME64x crates (Figure 3), which support hot swap of I/O modules. This system makes it possible to replace or add an I/O card without shutting down the crate. Furthermore, the crates are equipped with a comprehensive fan-failure warning system.


Other key features of VME64x installed at the Swiss Light Source include the ability to support slot keying, geographical addressing, better EMC performance, more ground pins, and more user defined IO pins. VME64x IndustryPack carrier boards are also being used, which allow the choice of hundreds of IP modules.

Hytec has delivered over 800 VME64x modules and IP (IndustryPack) cards that provide support to the Green Springs IP standard. SLS has purchased a large quantity of 16-bit ADC and DAC IP cards that incorporate large memories. Transition boards have been developed to support the range. EPICS drivers have been developed to support the VME64x range of digital I/O (8001), ADC (8401), and DAC (8402) modules.

About the author
After a period of training and working for a number of electronics companies, Richard R.T. Tatham, started Hytec Electronics Ltd over twenty-five years ago. Initially set up to provide a service to government laboratories in the United Kingdom, such as U.K.A.E.A. (Harwell & Culham Labs.), The National Physical Laboratory, and the Particle Physics market, the company soon developed a reputation for developing novel solutions to measurement problems. Richard, Managing Director of Hytec Electronics Ltd., still very much a hands-on engineer, acts in the role of chief engineer and loves nothing more than shaping the new product designs and guiding the development staff towards another successful product.

Building on his early experience, Richard rapidly expanded Hytec into the Public Utility Sector. Hytec soon gained an international reputation with installed equipment worldwide and a client base including a wide selection of organizations in industry, research, and commerce. Richard has used his experience to good effect and has provided encouragement and support to other budding entrepreneurs. Additionally, he has held a number of external Directorships over the years. He is a founding partner of Vista Control Systems Inc in the USA formed by a talented team from Los Alamos National Laboratory that develops control and data acquisition systems. For more information about the company and its products, contact:

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