ELEX launched a new control system for its products

Traditionally, automated modules for the production of radiopharmaceuticals produced by ELEX used PLC-based control systems, where the complete production process was hard-coded into the PLC. This provided extremely reliable operation of the modules, even if the communication with the notebook computer running the graphical user interface (GUI) has been lost during the production. However, any modification of the process required a service intervention for replacing the firmware in the PLC.

As a result of close collaboration between ELEX, Pixelablaze (a software development company) and Mikro Kontrol (a company building the control systems for our products), a conceptually new control system has been developed. The process is still controlled by the PLC, however the procedure is defined as a sequence of operations interpreted by the PLC. The innovation is that the sequence is not decoded by the notebook computer and sent line by line to the PLC as other competing control systems do; rather the whole sequence is downloaded into the PLC prior to the start of the synthesis and a built-in interpreter in the PLC is decoding the sequence. This way, the modification of the process is simple, as the operator himself can change the sequence on the notebook computer, while the reliability of the control system is not compromised: even if the communication between the PLC and the notebook computer has been lost, the PLC will complete the process, since the whole sequence is in its memory.

The innovative sequence language developed for this purpose has a rich set of commands, including instructions resembling the commands of high level computer languages. The operator can create procedures which can be called upon as subroutines (subroutines can also call other subroutines); one can issue direct jumps to a dedicated line (the line addresses are symbolic for user friendliness); there are branching possibilities based on the live values of process signals; there are user configurable message windows, which can be used for branching; one can even dynamically create  menus for executing certain routines in semi-automatic mode of operation, just to name a few.

Another significant enhancement of the control system is a graphical editor for sequence generation: the whole sequence can be prepared by simulating the manual operation of the system, i.e. the appropriate command lines are generated by simply clicking by the mouse on the icon of the hardware on the screen. The whole simulation is “live”, i.e. one can see the simulated status of the system on the synoptic screen as if the system would be in operation. This way, the development of new sequences is straightforward and the modification of existing sequences is simple and user friendly. The new graphical editor, Squeed, operates as an add-on to the traditional SCADA application.

We hope that radiochemists using our equipment will acknowledge the user friendliness of this new control system.