1. Vacuum Control System AdV architecture similar to the existing one one autonomous station per “pumping unit” (about 30 units : tower, tube station, cryopumps …) low level hardware interlocks other protections (cleanliness for example) at software level monitoring and steering of the whole system from a single place Some constraints reuse existing hardware EMC compatibility and other noises (fans, …)

2. Design issues The main problem is the definition of the central unit for control. There is a large amount of I/O (One UHV tower = 65 Digital Inputs, 20 Digital Outputs, 10 RS232 ). Two solutions are possible : PLC and PCI. PLC : standard industrial solution long-term maintenance OK reduced amount of software to be written no EMC problem handling of RS232 links limited intelligence (depends on PLC) PCI (similar to the current OS9 solutions ): easy handling of various interfaces large computation power more software to be written EMC long-term maintenance

3. New cost estimates Cabling : cost for 1 tower  2  cost for tube station Total  150 k€ Computing units (estimations with current IO) : PLC : Crouzet : not enough powerful Wago :  3 k€/station. But one PLC is able to handle only 5 RS232 links. Need to handle two PLC on a single device. Becomes tricky. Moreover, no profibus for new devices except using other PLC costing 10 times more   15 k€/station Schneider :  15 k€/station. Luxury PLC because you need to handle 5 RS232 modules. Moreover, each RS232 module which costs 1200 € each Siemens :  15 k€/station. Similar problem with RS232 : 1 link by module, (550€/module)  10 modules  big PLC (3 k€) CPU : National Instruments :  15 k€/station For the moment, in any case, we reach 400 k€ for the computing units and a total of 550 k€.

4. New cost estimates Reusing existing devices with existing RS232 links is a major constraint on the design and significantly increases the cost. About 100 k€ could be saved if they are removed. Moreover, the use of RS232 links prevents to move the crates far away from the towers to avoid disturbances. Our conclusion is that the possibility of changing the RS232 interfaces should be carefully investigated by EGO vacuum group before any decision on the control system design.