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SLS Timing Master

SLS Timing Master

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SLS Timing Master

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  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

  5. 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 ioc’s (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.)