Diamond, a third generation of 3GeV synchrotron light source, commenced operation in January 2007. The SR (Storage Range) is based on a 24-cell double bend achromatic lattice of 56lm circumference. It uses a full synchrotron of energy booster and a Linac for injection. The output of spectral is optimized for high brightness up to 20 keV from undulators and high flux up to 100 keV from multiple wigglers. The recent operational state includes seven photon beamlines, with a further fifteen beamlines under design and construction now.
The Diamond design control system is based on the EPICS control system toolkit. It uses VME and other IOCs as the primary plant interface. The VME systems undertake plant operation and supervision within defined limits but do not protect equipment from damage. Below the systems of VME there is a PLC based subsystem to ensure correct operation of process based equipment i.e. cryogenic systems and protection of equipment.
The requirement for PLC hardware on Diamond as following:
• Good user based
• Establish supplier
• Product support
• Choice of input and output interface types
• Long product availability
• Minimal cost
• Accepted by industry for turn key contracts
• Capable supporting process based on applications
• Communications interface preferable Ethernet
• Good program development environment
• Open standard program specification preferable IEC61131-3
In considering the requirement for a PLC on Diamond it would have been preferable to have selected one set of hardware and one supplier. However, this would have meant compromising on number of important requirements most notably minimal cost. The solution to this was to recognize that the requirements could be best met with two platforms, a high end platform addressing process control requirements and well accepted by industry but at a premium cost and a low end solution addressing all other requirements and reduce the cost.