SNS Timing Master LAUR03 3377 Eric Bjorklund SNS

SNS Timing Master LA-UR-03 -3377 Eric Bjorklund SNS Integrated Control System

Basic Characteristics l Event System. – 256 events possible. 25 events currently in use. l ~5 millisecond machine cycle. 60 Hz. – Option to go to 120 Hz. when second target added. l 10 second super-cycle. l Clock synchronized with ring RF. – Ring RF is 1. 057767 Mz at 1 Ge. V – Clock is 32 X Ring RF SNS Integrated Control System

Timing System Components RTDL GPS Master Timing IOC Event Link Experimental Halls 10 MHz Crystal Osc. SNS Real Time Data Link Master Timing Slave (V 124 S) X 32 PLL (33 MHz) SNS Event Link Master Machine Protection System Ring RF AC Line ICS IOC's Timing Reference Generator SNS Utility Module LEBT Chopper Neutron Choppers Timing System Hardware Diagnostics Subsystem Hardware Timing System Users Experimental Systems SNS Integrated Control System SNS Time Stamps Beam data RF Gates Extraction Kickers Tx. HV Gates High resolution timestamps Machine Modes SNS Timestamps Remote Reset Synchronous ISR’s *4 PLL (64 MHz) Beam Delay Beam Phase Micro pulse width Macro pulse width SNS Time stamps Delays Gates Triggers

Two Transmission Links l Event Link – Transmits the timing events that define a machine cycle. – Each event is 8 bits plus parity (256 events maximum). – Clock is variable and derived from the ring revolution frequency (32 * Frev). – Events 0 – 63 are generated by the timing system hardware. – Events 64 – 255 are generated by software (no fixed times). l Real-Time Data Link (RTDL) – Transmits machine parameters and data prior to every new cycle. – 128 frames possible (expandable to 255). – Each frame contains an 8 -bit frame number, 24 -bits of data, and an 8 -bit CRC. – Clock is 10 MHz. SNS Integrated Control System

Sample RTDL Data Frames Frame Number Data 1– 3 Time of day 4 Event link period 5 MPS mode 6 60 Hz phase error 7 Beam Width 15 IOC Reset Address 17 Pulse Flavor 18 -21 RF Gate Widths 24 Previous Pulse Status 25 Cycle 255 24 -bit CRC (calculated) SNS Integrated Control System

Timing Master Crate Layout (Reserved) RTDL Input Module (V 206 S) VME Bridge Event Monitor Frequency Counter Trigger Module (V 124 S) Trigger Module (V 124 S) Event Link Input Module (V 101 S) Line Synch Module Event Link Master (V 123 S) Event Link Input Module (V 101 S) 21 20 19 18 17 16 RTDL Input Module (V 206 S) 9 15 RTDL Input Module (V 206 S) 8 14 RTDL Input Module (V 206 S) 7 13 RTDL Input Module (V 206 S) (Reserved) Utility Module Processor SNS Integrated Control System RTDL Input Module (V 206 S) RTDL Master (V 105 S) 6 12 9 RTDL Input Module (V 206 S) Utility Module 5 11 8 RTDL Input Module (V 206 S) GPS Interface 4 RTDL Input Module (V 206 S) VME Bridge 3 10 7 6 5 4 3 2 1 21 20 19 18 17 16 15 14 13 12 11 2 10 1

Event Link Generator Hardware l Event Link Master Module (V 123 S) – VME Module. – Generates event link carrier (~17 Mhz). – Accepts, prioritizes, and transmits “hardware” and “software” events. l Event Link Input Module (V 101 S) – VME Module for generating “hardware” events. – Communicates with the event link master module over the VME P 2 backplane. – Hardware events generated from TTL inputs to the V 101 S – 16 events per module. SNS Integrated Control System

RTDL Generator Hardware l RTDL Master Module (V 105 S) – VME Module – Generates the 10 MHz RTDL Carrier Signal and the RTDL frames. l RTDL Input Module (V 206 S) – VME Module. 8 frames per module. – Stores the data frames to be sent each cycle on the RTDL. – Communicates with the RTDL master module over the VME P 2 backplane. SNS Integrated Control System

Additional Modules l Timing Reference Generator – Double-Wide VME module. – Provides the 60 Hz “Cycle-Start” signal to the event link master module (V 123 S). – Uses a PLL to track the AC line zero-crossing and “smooth out” power grid frequency fluctuations. – Resolves the “conflict of interest” between power supplies that need to be “line locked” and the neutron choppers’ need for stable timing. l Frequency Counter – VME Module in the Timing Master crate. – Used to monitor the frequency of the event link clock. – Frequency is broadcast on the RTDL and sent to the timing reference generator to compensate for changes in the ring revolution frequency. SNS Integrated Control System

Additional Modules l GPS and GPS Interface Module – GPS provides time source and NTP time service to the site computers. – VME interface card captures the GPS time at each “Cycle Start” time. – Captured time is sent out on the RTDL. l Event Link Monitor – Monitors the event link and records which events occurred and when. – Buffers one full “Super-Cycle” (10 seconds). – Used by the event-link part of the time line monitor to make sure the event link is correct. SNS Integrated Control System

Machine Cycle Timeline Time Critical Events, (soft events disabled) Informational Events, non critical timing RTDL parameter transmission (for next cycle) Real-Time Data Link (RTDL) MPS FPL RF & High Voltage Events Cycle Start Beam On Event Link Snapshot, 1 Hz, 6 Hz, etc… Extract MPS FPAR System xxx Trigger Events Mostly Stable Triggers End Injection RTDL Transmit (Alternate) Cycle Start Extraction Kicker Charge RTDL Valid Beam On Range Allowed Range for Variable Triggers beam accumulation Anytime Machine Line-Synch Reference Clock +60 Hz Zero -60 Hz Zero Crossing 0 1 ms 2 ms SNS Integrated Control System 3 ms 4 ms 5 ms 6 ms 7 ms 8 ms

The Product and the Perpetrators SNS Integrated Control System