dirk zimoch, epics collaboration meeting, vancouver 2009 real-time data transfer using the timing...

Dirk Zimoch, EPICS Collaboration Meeting, Vancouver 2009

Real-Time Data Transferusing the Timing System

(Original slides and driver code by Babak Kalantari)


Real-Time Data TransferReal-Time Data Transfer

Key Hardware Features

■Event rate max 125 MHz■8 bit event code + 8 bit signals

or data (multiplexed)■Real-time data transfer rate

max 62.5 Mbytes/sec■At 1kHz linac repetition rate:

~60 kBytes/bunch



Event System Overview

Event

Generator

Fan out

ext. signals

EventReceiver

EventReceiver

EventReceiver

Event Stream

Timing IOC

• local delays• programmable pulses• on/off signals• real-time data

Ref. clock master osc.

FO links

50Hz mains

8 bit data 8 bit event 8 bit signals 8 bit event



Sources of Real-Time Data

■ Master timing IOC: real-time■ Other IOC: network latency but synchronous■ Upstream via timing system: real-time

Event

Generator

EventReceiver Event

Receiver EventReceiver

EventReceiver

EventReceiver

Timing IOC

IOC2

FO links

IOC3

IOC4

IOCn

Network

EventReceiver

IOC1

Fan out



Driver Software

■ Real-time data is seen as buffer of 2048 bytes►Variables can be mapped to offsets►Event generator and receivers have to agree on mapping►Send buffer on write or on trigger► Interrupt on buffer receive

■ Configuration in startup scriptmrfDBuffConfigure ("device", cardno, eg)

■ Still some work to do►Endian issues►Scheduling



Device Support

■ Generic device support for blocks of registers►Originally designed for S7 PLC communication over ethernet►Supports all standard i/o record types and data types►Process input records "I/O Intr" (with high priority)

■ Examplerecord (ai, "($NAME)") {

field (DTYP, "regDev")field (INP, "@evr/16 T=FLOAT")field (SCAN, "I/O Intr")field (PRIO, "HIGH")field (PREC, "6"

}

device name

offset in bytesdata type



Example Real-Time Data

■ Bunch train counter►32 bit int ►double (52 bit mantissa)►3 day test shows 100% reliability

■ Other beam parameters►bunch train length, energy, …

■ With upstream data: measured parameters► intensity, position, …

overflow in 16 months (at 100 Hz)good for 1.4 million years



Application Synchronization

(e.g. synchronous camera and current monitor trigger)1.Application sends code to timing master2.Event system distributes application code3.IOCs arm devices depending on code4.Devices acquire data synchronously

Exp. 2

Exp. 3

Exp. 4

Exp. 1

dev. 1

dev. 2

dev. 3

dev. 4

Beam source

dirk zimoch, epics collaboration meeting, vancouver 2009 real-time data transfer using the timing...

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