Accelerator Controls as they pertain to Instrumentation

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Accelerator Controls as they pertain to
Instrumentation

• My narrow view of the subject.

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Topic List

• Timing and Links
• TClock, BSClock, MDAT
• Common Hardware
• ACNET (Accelerator Control NETwork) and Consoles
• What is ACNET?
• Devices
• Application Pages
• Front Ends and AOCs (CAMAC, Embeded Systems)
• Examples (using LabVIEW)

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Definitions
FTP Fast Time Plot Used to plot live data at rates up to 720Hz
MADC Multiplexed ADC Generic 64 Channel digitizer up to 100KHz
MOOC Minimal Object Oriented Communication Used in embedded front ends to communicate data to ACNET.
CAMAC Computer Automated Measurement and Control Used to controls power supplies, provide timing, and perform ADC/DAC functions. Black crates and cards (usually).
ACNET Accelerator Control Network Central point for accelerator control. Data from Front Ends in, and operator response out.
OAC Open Access Client Java program running without user interaction and performing some task. EX Math OAC, TFW Emittance OAC
BSCLK Beam Synchronous Clock Encoded clock which enables user to find out when beam is at his location. Each machine has its own.
TCLK Tevatron Clock Used to transmit commands to system around the complex
MDAT Machine Data Used to transmit machine parameters to sys
DAE Data Acquisition Engine Used by OACs and Loggers to get data from Front Ends
VxWorks Development Platform for VME
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Timing and Links

• www-ad.fnal.gov/controls/hardware_vogel/index.html
  
• CAMAC
• Computer Automated Measurement and Control
• All kind of hardware modules available to do
  timing, triggering and DAC/ADC functions
• Why do we need Clocks?
• Easy way to synchronize and inform remote systems

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TCLK (Tevatron CLocK)

• Used to transmit Accelerator State to remote
  systems
• 10MHz encoded signal
• 256 possible values from 00 to FF
• Events sent out are generated by the TCLK
  generator depending on the Accelerator Timeline
  requested
• Some common events
• 00 Super Cycle Reset (timeline goes back to
  time 0)
• 07 Sent out at a 720Hz frequency
• 0F Sent out at a 15Hz Frequency
• 29 Stacking Cycle started
• 2A Pbar Injection into Main Injector
• 2B Proton Injection into Main Injector
• Used by instrumentation to listen to some
  specific events happening in the Accelerator (ex.
  shots to Tevatron)
• Also available over Ethernet Broadcasts.

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How the Encoding Works

• The modified Manchester code utilizes cells
  transmitted at a 10 Mhz rate that is, one cell
  every 100 nanoseconds This compact scheme uses a
  biphase signal and is defined so that if the
  phase, logic high or low, does not change over
  the 100 nanosecond period, the bit is 0. If
  there is a transition at mid-cell, the bit is
  1.
• If there are no events going out on the clock, as
  is the case some of the time, a solid string of
  ones will be broadcast. The bit before an event
  will always be 0 to distinguish it from
  background. At that point the clock decoders,
  like operators on an owl shift, must wake up and
  listen to the incoming message. The event itself
  will be 800 nanoseconds (8 bits) long, to be
  followed by a parity bit and at least 2 ones to
  reestablish background. This means that events
  can be sent out no closer than 1.2 microseconds
  apart.

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Sample Timeline Anti Protons to TEV

• 91-Pbar Reset to unstack Pbars for Extraction
  from Acc to MI
• 2A-MI Reset for Pbar Acceleration Cycle
• 40-Tevatron Reset for Pbar Injection at 150 GeV
• 9A-Accumulator Reset Extraction of Pbars to MI
• 94-TCLK reflection of MIBS 7A Pbar transfer
  from ACC to MI
• 5B-TCLK reflection of MIBS 7B Collider Pbar
  Beam Transfer Trigger from MI to Tevatron
• 2F-MI Cleanup
• 26-End of MI Ramp Flattop

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TCLK Demonstration

• This piece of LabVIEW code listens for a TCLK
  event to happen and informs the user.

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BSCLK (Beam Synchronous CLocK)

• TVBS, APTVBS, MIBS, RRBS
• Accelerator Frequency (53MHz)/7 encoding
  frequency
• TVBS, APTVBS and MIBS have AA revolution markers
• These are guaranteed to happen synchronously to
  the beam passing a specific location (with a
  stable delay)
• Beam Transfer Events are really generated on
  BSCLK, and reflected on TCLK.
• Usually used together with TCLK to determine
  trigger timing for Instruments
• Not available over Ethernet Broadcasts (very well
  timed and does not lend well to TPC/IP delays)

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MDAT (Machine DATa)

• Used to transmit machine parameters
• Beam Current, Energy, Time of Day, and Machine
  States
• 10MHz encoded signal
• Relatively few frames actually contain data
• Some of the frames are broadcast on the same link
  as the TCLK, but no real need to listen to them
  (yet)
• Instruments have the ability to transmit MDAT
  frames
• Tevatron FBI does this (frames 7X)

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Hardware used to provide Timing

• UCD (Universal Clock Decoder)
• Resides in VME, VXI or PMC bus
• Has inputs for the TCLK, BSCLK, and MDAT and
  memory for the decoded values
• Can produce TTL outs on specific events with
  programmed time delays
• RFT (Radio Frequency Timer) with PLL (Phase Lock
  Loop)
• Uses BSCLK AA frame with a delay to run a
  programmable trigger pattern
• PLL allows to get beam RF frequency by using the
  Beam Sync Clock

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What is ACNET?

• Communication protocol that supports
  communication between independent tasks on
  separate processors
• Basically a common way of encapsulating data
• In some ways similar to TPC with a header and
  body of each message
• DAE/Console requests data from the Front End and
  scaling from the Database. Once data is returned
  from FE and scaled, it is presented to the user.
  Similar for Settings.

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Some Sample ACNET Pages
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ACNET Pages II

• Perform many different tasks
• Display devices for the user
• Control instruments
• Definitions
• Parameter Page
• used to display a list of parameters
• Can start FTP and Snapshot Plots
• Standard used in many places
• Application Page
• Provides control and read back of some specific
  device (instrument, magnets)
• Most instruments have one of these

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ACNET Devices

• Exist in a Database and are editable through D80
• Usually decoded as numeric values but can
  represent complex data structures
• Names consist of a prefex followed by a
  followed by the name(6 characters)
• Prefixes can be I ( Main Injector) , T (Tevatron)
  , R (Recycler), L (Linac), B (Booster), A
  (Accumulator), D (Debuncher), Z (Testing), E
  (Experiment), V (State)
• Most are used by Front Ends (instruments) to
  report results, while a select few can embody
  states of the complex

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Example of Devices

• This demonstrates a reading of a device
  (Temperature), a setting of a device, and
  listening to a State Device Change.

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Front Ends

• 3 basic types
• CAMAC
• One per accelerator
• Runs timing cards, MADCs, magnet ramp cards
• No real software (ACNET devices let you control
  the hardware performance)
• Embedded Front Ends
• VME (usually) systems
• Use MOOC/ACNET to communicate to controls system
  and have means of reading out or controlling some
  aspect of accelerator operations
• OACs
• Usually JAVA based devices (can be written in C)
• Have no direct connection to the Accelerator
  Operation
• Collect and manipulate data that is produced by
  other Front Ends