1. Front End Driver (FED) Crates and Racks +Tracker PSU racks
Matthew Pearson
RAL
Electronics Week November 2002
Matthew Pearson
21/02/2019

2. Considerations How many FEDs per crate? How shall we arrange the FEDs?
Don’t mix FEDs from different partitions
In crates?
In racks?
Separate into +/-?
Do we need to reserve space in case we need to use more
FEDs than we expect? (if data rate per FRL is >200Mbytes/s)
Can we keep the S-LINK64 short enough?
(Has to be less than 15m)
Matthew Pearson
21/02/2019

3. How many FEDs per partition?
440 FEDs in total
4 Partitions: TEC+, TEC-, TIB+TID, TOB
Partition Layer #FEDs
TEC (1-3,4-6,7-8,9) (40,32,16,8) = 96
TEC (1-3,4-6,7-8,9) (40,32,16,8) = 96
TIB+TID 2*(1,2,3,4)+2*(1,2,3) 2*(12,16,6,8) + 2*(5,5,5) = 114
TOB *(1,2,3,4,5,6) *(11,12,7,8,14,15) = 134
What’s the best way to arrange these?
Note: Data rate per FED is highest for TIB1 and TEC7,8,9
Matthew Pearson
21/02/2019

4. How many FEDs per crate?
VME64 crates have 21 9U slots (see reference 1)
17-19 FEDs per crate ---- Depending on other
modules used.
Other modules:
Spare slots (eg. Tester board)
1 or 2 less slots in each crate
FMM (Fast Merging Module)
Or something similar, which may
be a transition card on the back-plane.
1 less slot in each crate (?)
Crate or rack controllers?
1 less slot in each crate
Matthew Pearson
21/02/2019

5. Crate/Rack Controllers
Remote PC based crate controllers are favoured.
Need VME interface module in each crate
Interface module has to be 6U
A 6U module needs 6U-9U adapter.
(only takes up one slot) 6U 9U
Frame
400mm
160mm
VME Backplane
Matthew Pearson
21/02/2019

6. Number of crates Partition #Crates TEC+ 6 TEC- 6 TIB+TID 7 TOB 8
Assume a given crate contains FEDs from only 1 partition.
If 17 or 18 FEDs per crate:
Partition #Crates
TEC
TEC
TIB+TID
TOB
For 19 FEDs per crate:
Partition #Crates
TEC
TEC
TIB+TID
TOB
Matthew Pearson
21/02/2019

7. How many racks? Don’t mix partitions in a rack. Partition #Racks*
07/16/96
How many racks?
Don’t mix partitions in a rack.
Partition #Racks
TEC
TEC
TIB+TID
TOB
TOTAL: 10 racks
true for both 17 or 18
FEDs per crate.
for 19 FEDs per crate we
save one rack.
…also, dedicated DAQ racks for each partition (64 FRLs per DAQ rack).
3 crates per rack *
Matthew Pearson
21/02/2019

8. Suggested FED rack layout*
07/16/96
Suggested FED rack layout
1.0m m
A B C
Need PC racks for
FEDs and DAQ
FED racks are grouped
to assist in cabling
(Francois)
Each DAQ is close to
FEDs from same
partition
DAQ DAQ
TIB+TID TOB
TIB+TID TOB
TIB+TID TOB
DAQ DAQ
FED PCs DAQ
DAQ DAQ
TEC TEC+
TEC TEC+
TEC TEC+ 11 12 13 . *
S-LINK length minimised (<10m)
Matthew Pearson
21/02/2019

9. TIB+TID Crates Assuming 17 FEDs per crate FRLs TIB4 (16) TID3 (10)
(The number of FEDs in each crate is shown in brackets)
FRLs
TIB4 (16)
TID3
(10)
TID1
FRLs
TIB2+
(16)
TID2+
(5)
TIB1+
(12)
TID2-
(5)
TIB2-
(16)
TIB3
(12)
TIB1-
(12) B1 B2 B3 B4 B5
Matthew Pearson
21/02/2019

10. TOB Crates FRLs TOB1 (17) TOB1 (5) TOB2- (12) TOB5+ (14) TOB3 (14)
(15)
TOB6+
TOB4 (16)
FRLs
TOB2+
(12) C1 C2 C3 C4 C5
Matthew Pearson
21/02/2019

11. TEC+/- Crates FRLs TEC1-3 (15) TEC1-3 (10) TEC4-6 (16) TEC7-8 (16)
C7/B7
C8/B8
C9/B9
C10/B10
Matthew Pearson
21/02/2019

12. S-LINK64 cable length the S-LINK cable lengths between FEDs and
The S-LINK64 standard will be used for the FED-FRL connection.
If using S-LINK PCI source card on VME transition card,
the link runs at 66MHz.
This has been shown to be OK for cable length of 15m.
Therefore:
the S-LINK cable lengths between FEDs and
FRLs of <10m are OK.
Matthew Pearson
21/02/2019

13. Some other S-LINK points
We would like to run FED at 40 or 80MHz (320 or 640Mbytes/s).
For convenience
To run as fast as possible
(to cope with unexpected high data rates)
If FED runs at 80MHz, we will get back-pressure signals from the S-LINK source card.
An alternative is to drive the S-LINK directly from the FED FPGA.
We could then run at any speed up to 100MHz (the S-LINK standard limit) – but would prefer to run at 80MHz
This would place tighter restrictions on the S-LINK cable length. How much tighter?????
Matthew Pearson
21/02/2019

14. Tracker PSU racks Current base-line plan is to place TK PSUs
in the Experimental Hall (UXC55).
20 racks for SST
2 racks for Pixel
4 racks for 48V DC PSUs
(estimates from Horst)
Allocate space:
2*9 racks on Upper Balcony in central position
2*4 racks on Middle Balcony in central position
Still things to consider (accessibility, maintenance, cost,
radiation and magnetic field issues ...)
Matthew Pearson
21/02/2019

15. Summary A scheme has been presented detailing the FED
layout within the crates and racks, and the placement
of the racks in USC55.
Note:
If the scheme is approved, and once the cables
are cut by Francois, nothing can be changed.
Matthew Pearson
21/02/2019

16. References Technical specification for subracks for LHC experiments
2. The S-LINK 64 bit extension specification: S-LINK64
3. CMS DAQ: Technical Design Report
4. Rack layout in USC55
Matthew Pearson
21/02/2019