SLS Timing Master

1
SLS Timing Master

• Timo Korhonen, PSI

2
Outline

• -What is a Master Pattern Generator
• -SLS operation
• -Possibilities of the SLS/Diamond-type system

3
Master Pattern Generator

• generates and distributes data to modify beam
  operation pulse-by-pulse
• typically a bit pattern to tell what kind of beam
  is coming next, where it should go and what
  devices should trigger in the next cycle
• in (ring) light sources with a single-purpose
  injector this is usually not (very much) an issue
  
• concept is unknown to many

4
SLS Operation

• Single type of operation inject from linac to
  booster to storage ring
• Sequence of events is always the same
  pre-programmed with EPICS records
• Slow changes of mode
• Top-up, parasitic linac measurements, booster
  tuning
• Implemented with EPICS tools, operation
  synchronized with timing system

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SLS Operation

• Example implementation top-up
• When injector is idle, e-gun, kickers and magnet
  ramps are turned off
• Ramping starts a few cycles before injection (to
  warm up the magnets), kickers also a couple of
  cycles before injection
• Bucket numbers to fill are sent (well in) advance
  to the related iocs (as waveforms)
• The cycle is started by master timing ioc sending
  an topup-on event (start e-gun triggers), and
  stopped with another event.
• No other data is sent with the events
• With our cycle time (3 Hz), sending the required
  data in advance (to not to rely on network
  response time) and a bit of organization the
  system works fine
• No big safety issues

6
SLS Operation

• Other sequencing has no big real-time
  requirements
• Measurements with linac between injection cycles
  drive in a screen monitor, turn on the data
  acquisition (camera triggers). Reverse procedure
  when injector needed
• Real-time data transmission was not a (big) issue
  for us
• we had to learn the limitations in CA response,
  though (like sending a list of bucket numbers in
  advance)

7
Pattern generator using the event system

• For other facilities, the real-time requirements
  are more strict
• CA-based approach would not be enough
• Can the (Diamond) event system be used in a
  master pattern generator
• What modifications would need to be done?
• What kind of software tools would be needed?

8
Possibilities of real-time data transfer with the
event system

• The APS event system has 8-bit frames for events.
  For SLS, we (mainly for technical reasons)
  decided to make the frames 16-bit.
• However, retained the 8-bit wide event codes for
  SW compatibility
• The remaining 8 bits are free (although we
  found use for them distributing clock signals
• By modifying the firmware they can be used for
  data transfer
• Also the frame size could be changed (64, 128,
  256,bits)
• This implies a change in the frame rate (events
  per second)
• The Diamond event system cards have (for Diamond
  specs) a frame rate of 125 MHz (with 16-bit
  events)

9
Conclusions

• The hardware should have enough capacity (128
  MB/s using the idle channel)
• Would be good to agree on the data transfer
  method to avoid too many firmware versions and
  too many EPICS support versions
• What kind of software tools are necessary to
  generate the patterns?
• For a slow-cycling light source with a dedicated
  injector, the need is not immediate (but might
  be, depending on the outcome.)