Integrating Acquired Subsystems

Bob Dalesio 09/21/99

Attempting to Understand the Issues to Effectively Acquire Subsystem Controls

• To understand the issues involved, we look at three subsystems that were acquired for LEDA: I. RFQ Vacuum Control, II. RFQ Resonance Cooling Control System, III. High Power RF Control.

• For each system we will look at the function provided and the approach taken to divide the work between the provider and LANL as well as the time taken to perform the functions of requirement development, application, and integration.

• Finally we suggest approaches that may reduce the time to complete a fully integrated and maintainable subsystem.

I. RFQ Vacuum Subsystem

• Livermore developed in Labview with Modicon PLCs and Granville-Phillips Ion Gauge Controllers for approximately 930 signals.

• By agreement, the PLCs contained vacuum interlocks and automatic startup was done in Labview.

• Livermore developed the system stand alone on their site and installed and checked it out at LANL.

• Los Alamos converted the Labview portion over to EPICS and wrote the driver for the Modicon PLC.

• LLNL and LANL worked on the integration together.

RFQ Vacuum System Manpower Usage

• LLNL– 10 months to collect requirements and do project engineering

– 7 months to implement the vacuum system

– 1 month to install and test

• LANL– .25 month to work with LLNL for planning (3 meetings)

– 2.5 months to develop Modbus driver and adapt the GPIB and IP drivers.

– 1 month to develop screens (more extensive set - including interlock displays)

– 1 month to develop the database

– .5 months to test and integrate (only testing connection to the PLC)

• Notes– New interlock to HPRF required within 15 msec - RFQ PLC could do 40 msec at the

current load so this interlock was done in an IOC.

– Strain gauge channels were added to the EPICS IOC directly.

– Drivers were re-used for HEBT vacuum, injector and injector vacuum.

II. High Power RF

• Continental Electronics provided the transmitter using an Allen-Bradley PLC5/40 for control. Maxwell Technologies supplied the power supply using an Allen-Bradley SLC 5/03 for control. Combined they have 215 signals with 2,700 additional database records - to support limits and gain constants.

• An Allen-Bradley Panel Mate was used to interface to the datahighway and provide a user interface to the PLCs

• Equipment was built and tested at the providers site and checked out on delivery.

• Los Alamos made modifications to an existing Allen-Bradley driver to support multiple masters controlling the I/O

• Integration was done by Los Alamos.

High Power RF Manpower Usage

• Maxwell and Continental– 12 months was the estimate given to produce the controls for the PLC systems.

• Los Alamos– 4 months to make Allen Bradley and scan task modifications required.

– 2 months to develop a network fault logger like the local one provided

– 12 months to develop the database

– 2 months to test and integrate

• Notes:– Conversion in PLC not consistent - required debugging and EPICS DB changes.

– PLC use of registers as scratch pad during scan cycle required PLC debugging.

– Complex logic for HPRF ladder logic increased debugging time.

– Control channels not implemented in PLC required debugging time

– Each change to the PLC took at least a week as there was no support for integration

– Limits and gains in PLC significantly added to EPICS DB size as each of these values had to be brought into EPICS as separate records - not fields of one record.

III. RFQ Resonance Control Cooling System (RCCS)

• Implemented by Allied Signal in EPICS for 1,020 signals.

• Built and tested at their plant and then delivered and tested at Los Alamos.

• Los Alamos took over maintenance after integration tests were complete.

RFQ RCCS Manpower Usage

• Allied Signal– 12 months to gather requirements

– 9 months to implement database (6 of them to train a new user)

– 3 months to implement Industry Pac drivers.

– 4 months to integrate and test - automation loops required tuning

• Los Alamos– Negligible time to offer some support.

• Notes– LANL had written the same drivers in parallel

– Allied Signal thought that they would have been more effective using a PLC

Analysis of Our Experience with Integrating Acquired Systems

• Having the requirements development occur where the equipment is being built greatly improves the result, reducing the time required to implement.

• People are most productive using tools that are familiar to them.

• Maintenance cost increase because the purchaser must train someone to take over maintenance of the subsystem controls.

• Integration requirements must be considered from the design phase.

• Subsystem control requirements are a subset of integrated control requirements - which do not all show up in a timely fashion.

Suggestions for Acquiring Subsystems

• Make simple systems easier to produce by using adequate tools that are familiar to the engineer implementing the system.

• Have local control engineers involved during all phases of the project - from requirements for request for bid through integration.

• Always be prepared for changing requirements!

• Make complex systems easier to produce and maintain by using a system capable of describing complex systems.