SLS Timing Master Timo Korhonen PSI Outline What
- Slides: 9
SLS Timing Master Timo Korhonen, PSI
Outline -What is a “Master Pattern Generator” -SLS operation -Possibilities of the SLS/Diamond-type system
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
SLS Operation • Single type of operation: inject from linac to booster to storage ring – Sequence of events is always the same; preprogrammed with EPICS records • Slow changes of mode – Top-up, parasitic linac measurements, booster tuning – Implemented with EPICS tools, operation synchronized with timing system
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
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)
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?
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)
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. )
