Mikolaj Cwiok, 10 June 2009 RPC Operation Day Towards LB configuration through TS: Improvements to CCU ring stability Mikolaj Cwiok – University of Warsaw for the Warsaw RPC Trigger Group 10 June 2009

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Presently CCU token-rings are needed for: 1. LB/CB configuration from Flash (e.g. after power on). 2. Setting up FEB thresholds, FEB monitoring. 3. Masking noisy strips. 4. Collecting LB/CB monitorables. 5. Changing LB/CB firmware stored in Flash. There are 18 CCU-rings (10 barrel + 8 endcaps) In the future: Tasks 1) & 3) will be initiated by a TTC command. Introduction Eth cables Opto fibers DOH Eth cables 1 CCU-ring = 6 LBBs = 12 CBs FE C Topology of a CCU ring

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Introduction Original concept for TRACKER needs

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Electrical part CCU copper signal cable: CAT6 Ethernet cable as a medium. 8 signal wires (4 twisted pairs). Common shielding + aluminium foil for each signal pair. In our case: 3 pairs are used for CLOCK, DATA & RESET signals, 1 pair is reserved for GND. It was decided some years ago that: – Ground pins and shielding should be connected to the CB ground only at one end (LVDS transmitter side) – Between UXC floors signal pins should be galvanically insulated by means of LAN-transformers (LVDS receiver side).

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Problems 1. RF pickups: Despite using CAT6 shielded Ethernet cables the external EM noise sources present in the UXC cavern (e.g. nearby power cables, some electric equipment) are capable to corrupt 40MHz CLOCK and DATA signals or to trigger unintended RESET signals. 2. Limited VME crate bandwidth: Happens when too many CCU operations are demanded by LBB XDAQs at the same time (we use 18 FECs in 3 CCS boards in the same VME crate). Examples of such “conflicting” tasks are: setting FEB thresholds, reading FEB temperatures, reading LB/CB monitorables, programming LB/CB Flash memories. I will not address this second issue in this talk.

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Grounding scheme (present) GND_pins GND_shield CCU cable GND_out GND_in LAN-trafo CBCB LB B GND_cb GND_lbb CBCB LB B GND_cb GND_lbb LVDS transmitter LVDS receiver Signal pins are not shown for simplicity LBBs in the same rack: LBBs in different racks on different floors: OK, we are avoiding ground loops......but now cables are susceptible to RF pickups! GND_pins GND_shield CCU cable CBCB LB B GND_cb GND_lbb CBCB LB B GND_cb GND_lbb LVDS transmitter LVDS receiver Signal pins are not shown for simplicity

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Tests in the lab The problem was reproduced at the test stand in Warsaw: - a 5 meter CCU cable connecting two CBs, - a 220V power cable parallel to the CCU one over the distance of 2 meters, - fluorescent lamp or electrical motor acting as a “noise generator” for 220V bus, - # of errors was counted directly on the FEC mezzanine by triggering on {LINK_OK=false} OR {FEC_ERROR=true} condition. Different solutions were tested, including: - small modifications of the Control Boards, - different cable shielding scenarios.

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Control Board improvements ● Before LVDS receiver for CLOCK, DATA and RESET signals: ● After LVDS receiver for RESET signals only:   2 x 50   nF  nF 100 

Mikolaj Cwiok, 10 June 2009 RPC Operation Day LBBs in the same rack: LBBs in different racks on different floors: Still no ground loops and RF pickups are significantly reduced now. GND_pins GND_shield CCU cable CBCB LB B GND_cb GND_lbb CBCB LB B GND_cb GND_lbb LVDS transmitter LVDS receiver Signal pins are not shown for simplicity Shielding improvements GND_pins GND_shield CCU cable GND_out GND_in LAN-trafo CBCB LB B GND_cb GND_lbb CBCB LB B GND_cb GND_lbb GND_external LVDS transmitter LVDS receiver Signal pins are not shown for simplicity

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Summary 1. A way to reduce RF pickups by CCU cables seem to be in hand. 2. Will try it on two CCU-rings first (15-19 June): - RB-2 NEAR → modify cables and CBs, - RB-1 NEAR → modify only CBs. 3. If this works, will modify CB and/or CCU cables on all other rings in July before magnet tests start.

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Backup slides

Mikolaj Cwiok, 10 June 2009 RPC Operation Day CCU rings for RPCs Example for Barrel and YE1 Example for Barrel and YE1

Mikolaj Cwiok, 10 June 2009 RPC Operation Day CCU rings for RPCs Optical part: Connects FEC with DOH on the CB Two redundant signal paths called “A” and “B”. Each path uses 4 fibres: CLOCK_in, DATA_in, CLOCK_out, DATA_out Two CBs are equipped with DOH mezzanines Electrical part: Two redundant signal paths called “A” and “B” Interconnects: 6 LBBs (12 CBs) in barrel wheels and YE1 disks or 3 LBBs (6 CBs) in YE3 disks. 3 differential signals: CLOCK, DATA, RESET CAT6 Ethernet cables having: 4 individually shielded wire pairs, common outer shielding grounded at one end 4 LAN transformers between UXC floors Currently ring “B” cables are disconnected from all CBs

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Control Board improvements Test of 5m cable

Mikolaj Cwiok, 10 June 2009 RPC Operation Day Final improvements