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Data Format for CKM. J. Wu, S. Hansen, M. Bowden, B. Haynes, P. Cooper For CKM Collaboration. Questions. (1) How data are generated? Undefined but some knowledge exists. (2) What’s impact after data streams flow through the event builder (switch)? Unknown but there are some guesses.

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data format for ckm

Data Format for CKM

J. Wu, S. Hansen, M. Bowden,

B. Haynes, P. Cooper

For CKM Collaboration

questions
Questions
  • (1) How data are generated?
    • Undefined but some knowledge exists.
  • (2) What’s impact after data streams flow through the event builder (switch)?
    • Unknown but there are some guesses.
  • (3) What are the requirements of the PC farm processors?
    • Unknown.
challenge
Challenge
  • Today’s TDC or ADC pumps out one digital number per CLK cycle.
  • Only the outputs with hit will be sent to DAQ. (Zero suppression).
  • CLK cycle information will be destroyed during zero suppression.
  • Time stamp (TS) must be attached to TDC or ADC data by designers.
example tdc

9 ns

09

02

03

04

05

06

07

08

09

Example: TDC

CLK

In

TDC

TS (8bits)

  • Channel is hit 9 ns after leading edge of the CLK.
  • At which CLK cycle?
  • At CLK cycle 05.
  • At 0005 or 1F05? or 2005? or 2105? … ? (Y2K again)
  • That is a challenge.
  • Using 16 or 32 bit TS? Not a solution.
ts counter roll over problem
TS Counter Roll-over: Problem

It’s hard to know in which century these events happened

17

86: Morzart wrote “Le nozze di Figaro”.

??

24: Beethoven wrote Symphony no. 9.

??

05: Einstein bought a new hat.

??

95: Windows 95 went to market.

Consider this chronicle record

??

08: LHC went to operation.

??

13: Fish became smarter than human being.

ts counter roll over solution
TS Counter Roll-over: Solution

Century of the dummy records can be identified

17

86: Morzart wrote “Le nozze di Figaro”.

18

00: Nothing important happened.

18

24: Beethoven wrote Symphony no. 9.

19

00: Nothing important happened.

19

05: Einstein bought a new hat.

19

95: Windows 95 went to market.

20

00: Nothing important happened.

20

08: LHC went to operation.

Insert dummy records…

21

00: Nothing important happened.

22

00: Nothing important happened.

Century of the events can also be identified

23

13: Fish became smarter than human being.

the solution is
The solution is:
  • Inserting a dummy record (roll-over marker) whenever the TS roll-over happens.
  • There is no step 2.
ts establishment
TS Establishment

TS10

Digitizer

Reset/Sync.

CLK

CLK

Sys.

No-op

DATA

Receiver

Serial Links, Optic fiber or LVDS pairs

TS32

PC Farm

Event Builder

(Switch)

hit data package
Hit Data Package

“Triggerless” scheme:

Use hit as guide.

Roll-over marker is inserted whenever counter roll-over, regardless there are hits or not in between.

Digitizer

Roll-over marker is inserted.

TS of hit is attached with hit data.

CLK

Sys.

Roll-over marker is inserted at beginning.

DATA

Receiver

PC Farm

Event Builder

(Switch)

data transmit format
Data Transmit format

Digitizer

More data and idle

CLK

Sys.

Emergency service request

Send hit data blocks when they are ready.

Emergency requests are serviced by CLK sys. and commands are sent back.

DATA

Receiver

When there is nothing else to transmit, send No-op and TS to maintain TS counters.

PC Farm

Event Builder

(Switch)

DAQ data flow

two types of digitizers for ckm
Two Types of Digitizers for CKM
  • TDC only channels: (chamber, RICH)
  • ADC+TDC channels: (veto systems)
example chambers tdc only
Example: Chambers: (TDC only)

Roll-over marker at later time

02

01

1

Channel etc.

TS of roll-over

2

00

TDC

0

TDC

TS of Hit

1

FF

FE

01

1

00

1

Channel etc.

TS of roll-over

0

FF

Roll-over marker

FE

05

TDC

0

TDC

TS of Hit

04

03

02

TDC

0

TDC

TS of Hit

01

0

00

1

Channel etc.

TS of roll-over

3

FF

Roll-over marker

Disabled 256 CLK cycles after reset

FE

example chambers data bitmap

15

8

7

0

Example: Chambers: (data bitmap)

Roll-over Marker

1

Ch. #

TS (10 bit)

TDC data

0

E

TDC (6 bit)

TS (8 bit)

D

Time (1ns/bin)

Earliest Time from CLK leading edge

Double hit marker

why transmit 8 bits ts
Why Transmit 8 bits TS?
  • Convenient
  • Less data volume
example g veto adc tdc data
Example: g Veto (ADC+TDC data)

5 MeV hit

E(MeV)=

3

1.5

0.5

Range

2bits

Roll-over Marker

14 bits

FADC

6bits

0

0

0

0

0

0

0

0

0

12

6

2

0

0

M

H

Header

14bits

T

TDC

6bits

Hitlet

example g veto data bitmap

15

8

7

0

Example: g Veto (data bitmap)

Roll-over Marker

1

1

E

Ch. #

TS (10 bit)

Hitlet Header

1

0

E

TS (10 bit)

0

0

QIE (TS1)

QIE (TS0)

QIE data

0

0

QIE (TS1’)

QIE (TS2)

TDC data

0

1

TDC (6 bit)

TS (8 bit)

0

0

0

0

0

0

0

0

0

12

6

2

0

0

M

H

T

from digitizer to data receiver
From Digitizer to Data Receiver

Digitizer Side

ch1

chN

ch0

Millenary

(=256

Centenaries?)

Hit data

Centenary

(=256 CLK

cycles)

Additional header with Centenary count

ch0

ch1

chN

TS roll-over marker

Data Receiver Side

pass through switch

Data Receiver Side

Pass Through Switch

ch0

ch1

chN

Inside PC Farm

The “only”

requirement is:

a Millenary must

stay together.

chN

Data of same

Millenary #

from different

channels are

sent to same PC

farm node.

ch0

It’s OK in

wrong

channel order.

ch1

to do
To Do
  • A lot of works must be done.
  • Better understanding on going through switch is needed.
the end

The End

Thanks