The Access Control and Interlocking is part of the Personnel Safety System (PSS) that is being developed for the IASA RTM. We have used PLCs (Programmable Logic Controllers) for both interlock and control functions. Although the appropriate data (I/O points, status information, faults, etc.) are sent to the EPICS database and can be displayed in any authorized workstation, the EPICS interface is not an integral function of the PSS operation (i.e., if the IOC goes down, the PSS function is not affected).
Above, a simple Access Control Interlock Diagram is shown, developed according to the needs of the Injector and 100 keV line project. The entrance door to the injector tunnel must be closed for either the high voltage or the beam to be on. Only for the case of high voltage there is the option of interlock bypass by an authorized person, while there can be no bypass whenever radiation is being produced.
For the realization of the Injector Maquette Project access interlocking, we have used the Programmable Controller shown in the photo above. This is the General Electric Series One programmable microprocessor.
The above diagram shows the Interfacing of PLCs with Binary I/O Units to the EPICS environment. Status signals from PLCs are interfaced to the VMEbus and thereafter analyzed with the VMIVME-2534 module. Once it is available as a collection of EPICS database records, this information can be used for validation, fault tracing, alarming or user training and debugging. Also, it is essential that the communication is a read-only operation (the database has not the ability to write into the PLC data space).