sns integrated control system timing clients at sns dh thompson epics spring 2003

SNS Integrated Control System

Timing Clients at SNS

DH Thompson

Epics Spring 2003


You Think You Have Problems

Your timing system dates from the 16th century and

predicts tides on the Thames

The Boss Looks Like This!

Then your timing system needs updating.


Timing Clients

Timing client hardware– V124– Diagnostics– Machine Protection System

Systems– Ion Source and Front End– Linac RF– Target Instruments– Machine Protection System– Diagnostics– Timing Master


Hardware Clients V124S

The V124S is based directly on the RHIC Design at BNL .

Receives 17 MHz. EL from timing master.

8 programmable gate outputs and one clock output with 63 nS clock sync resolution and fine delay.

FPGA Based design.


V108S Utility Module

V108 Utility module decodes EL and RTDL.– EL events can be processed as EPICS events by

processing event records.– RTDL frames are available as longin records in real time at

60 Hz. (Used to set gate widths from the timing master.)

Provides precise time to IOC from timestamp frames in the RTDL

Module also monitors crate voltages, temperature, and fan speed.

Provides 2 bits of I/O.– Example: Beam image camera gets trigger from EL in

software via V108 I/O


Diagnostics Embedded Timing CircuitFeatures of PCI card (NADS)

Temporary debug section

Low jitter (~10ps) clock circuitBalanced timing

system inputs (PECL)

Coax pulse and clock outputs (LVTTL)

Buffered general purpose I/O (68 pin connector compatible with commercial breakout chassis)

Single gate array- PCI Master/Target with scatter/gather DMA- Timing functions, real-time data buffers- ~100k gates left for application specific functions


Machine Protection System

Implemented on PMC Card and I/O Chassis. MPS Decodes EL/RTDL to provide 63 NS resolution of MPS trips

and time stamp MPS database records.– Used by correlator to find first trip.– Support added in drvTS so that device support could compute time

stamps.

Timing system is essential to MPS health while the MPS monitors timing system health.– 60 Hz cycle start event is required heartbeat.– Time stamp and other data on RTDL are monitored for reasonable

changes.

MPS and timing system are closely coupled– MPS derives its own clocks from EL

– Auto-Reset and Latched carriers drop on fault.

– Timing system gets fault events and status from MPS– MPS Adapts enabled inputs to beam flavor.


MPS Fast Protect Block Diagram


Source and Front End

Uses V124 8 Channel Gate Modules

The trigger control chassis which is the “head end” of the Machine Protection System. Outputs gates for ion source RF, Choppers, bunchers and RFQ.


Ion Source Control

Trigger Control Chassis Logic(simplified)

S

R

Q

QCycle Start

Beam Enable

To Source

MPS OK

Delayed Source

Source

S

R

Q

Q

Source Enable


Linac RF

Primary interface is V124 with optical fanouts to HV Converter Modules.

LLRF Uses several gate outputs including pre-pulse and RF on gate.

Gate start times and rep-rates are on Event Link. Gate widths are on RTDL, Utility module records set

V124 gate width on each LLRF and HPRF channel. Local variable rep rates and gate widths are available

at an IOC. This provides independent timing for DTL RF testing at same time as Front End operations.


Ring and Target

Ring Reference is source of EL clock but actual ring phase will sync to the EL’s cycle start.

Neutron beam line instruments at the target will have own timing system based on a high speed parallel-serial-parallel link. – Will decode EL/RTDL on PCI card.– Will manage chopper synchronization to machine cycle.– Will set instrument data acquisition timing and transmit both

accelerator vetos and chopper vetos to instruments.– Will support neutron time of flight measurements.


Timing Master

Uses 3 V124s to generate hardware timed events and generate some timed interrupts for the sequencer.– Sequencer schedules V124 Gates on or off according to

rep-rate pattern, to fire inputs on EL encoder.

EL will be monitored by EL Monitor as soon as driver is available.

Uses Utility module for environment but not time or events.


Improvements

Combine EL and RTDL on single 100/1000 MHz link based on Ethernet media devices.

The SNS Timing Master has few external events and no hardware RDTL data, so emphasis would be on pre-scheduling link using combination of software and table in FPGA. Still allow as many hardware events as needed within scheduled windows.

More of the gate scheduling could be done at the gates, fewer events & more reliance on cycle start and RTDL.– Gate Generator decodes cycle start + RTDL RF width, and cycle

number– Sets own delay and width based on data on timing link.– Rep-rate pattern stored in gate and used to enable output.– “Special” Cycles must still be supported.

Must maintain availability of the ring sync clock and line sync clock scheme.

sns integrated control system timing clients at sns dh thompson epics spring 2003

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