1. PS wire scanner failures
MSGW
27/03/2015
Jonathan Emery - Emiliano Piselli
BE-BI-BL

2. History
6 wire-scanner breakages since start-up in 2014 (2 PSB & 4 PS).
All linked to incorrect re-initialisation of the wire to its home position
Same hardware used without issues in 2012
Software modifications made during LS1 to add new functionalities revealed what are now known to be serious flaws in the wire-scanner firmware
3 distinct issues identified
Missing triggers
~2% of all requested scans are not triggered
50% of cases result in wire remaining in IN position (other 50% - wire remains OUT)
Recovery from IN position
If electronics loses track of wire position erratic wire movement can be provoked
Cause of latest breakage even with manual retraction
New procedure now in place to deal with re-start after such an event
No security on maximum initial drive voltage
Injector Wire-scanner Status Report IEFC R. Jones 6th March 2015

3. Beam wire scanner firmware
Motion control board with 3 on-boards FPGA
Operational versions untouched since 2009 (No problem until now… ????)
4 different Firmware version to match all the types of CERN: type: PSB-PS, type LINEAR (SPS and LHC), 2 types rotational in SPS
Intensive use has shown its limitations, impossible to be fixed by software.
Firmware release was mandatory in order to: 1) Have a safe InitHW sequence (return from IN position). 2) Add an extra safety to avoid the ‘reset home problem’. 3) Mitigate 1% of lost hardware triggers. 4) Return the scanner at home from every position. 5) Correct acquisition counter to avoid lost data. (software patch on-going to mitigate it)

4. Deployment history
PS and PSB version - Deployed successfully during March 19th stop to fix 1) to 4) - Software patch on-going for 5)
LHC version - Deployed successfully during March 19th stop with fix for 1) to 5) - Software address mapping changes on-going
SPS versions - 2 scanners types (RL and RS) still to be released - Software address mapping to change - Deployment could take place by April 13th 2015, if no other WS tasks and if access possible. (BA4 and BA5 access are needed)
1) Have a safe InitHW sequence (return from IN position). 2) Add an extra safety to avoid the ‘reset home problem’. 3) Mitigate 1% of lost hardware triggers. 4) Return the scanner at home from every position. 5) Correct acquisition counter to avoid lost data. (software patch on-going to mitigate it)
1) Have a safe InitHW sequence (return from IN position). 2) Add an extra safety to avoid the ‘reset home problem’. 3) Mitigate 1% of lost hardware triggers. 4) Return the scanner at home from every position. 5) Correct acquisition counter to avoid lost data. (software patch on-going to mitigate it)
1) Have a safe InitHW sequence (return from IN position). 2) Add an extra safety to avoid the ‘reset home problem’. 3) Mitigate 1% of lost hardware triggers. 4) Return the scanner at home from every position. 5) Correct acquisition counter to avoid lost data. (software patch on-going to mitigate it)

5. Conclusions
We have worked hard to get the firmware release and the lab tests done as early as possible
All the PSB and PS are actually heavily used and they all seem to work properly…right GUIDO????
We have learned something…good lesson for the new wire scanner…
We are available as much as possible in order to ensure good operation of the wire scanners!
Carolina Bianchini

6. PS wire scanners failures
People involved:
G. Baud, B. Dehning, J. Emery, A. Guerrero, L. Jensen, R. Jones, E. Piselli,
G. Sterbini
Thanks for your attention! 6