Prepared by Fred Borcherding, Sasha Golyash

1. Rice WorkshopPCrate LVThis document covers the LV system at the PCrate BP >> the hardware involved is the BP, the PCMB mounted on the BP, and the PCMB mezzanine board the ELMB. Prepared by Fred Borcherding, Sasha Golyash Rice Workshop PCMB

2. LV at PCrate • Two Problems with LV at the PCrate • 1 Lost CANBus communication with the ELMB on PCB at PCrate • 2 Unreliable configuration of the boards within the Pcrate upon startup • Problem 1 >> Lost communication with one or more ELMBs • Background – 4.5V and 6.5V power is delivered to the Pcrate BP from the Maraton. There it is converted to several 5.0V, 3.3V and 1.5V for 12 different channels for boards in the crate. The PCMB with its mezzanine ELMB plugs into the BP and alows a remote ON/OFF for each of the 12 channels independently and monitors the voltage of these multiple channels. • Loose communication and have to power cycle ELMB to reestablish communications • Done at Atlas PS in S4F04 >> no remote operation • This problem is seen with other ELMBs • CMS rack turbines contain an ELMB used for DCS control and monitoring • Frank Glege is in charge of this • The ELMBs in S1 and S2 turbines work perfectly • But serious problems with the ELMBs in cavern racks • Communication with some racks has never been established • Frank is pursuing this problem, we will follow his progress • Again it is not clear where the problem lies >> software interface or hardware • Meanwhile Frank suggests two action items for CSC • 1 review >> one of the builders of the ELMB is with CERN, we should contact him and review our system hardware with him >> I will pursue this and set up for end January • 2 CAN analyzer >> CMS has a CANBus analyzer that we should borrow and look at the hardware in our system. >> see discussion on Maratons – Petr and Sasha will pursue this in January • Startup >> a startup procedure has been developed to minimize this problem. Rice Workshop PCMB

3. LV at PCrate • Problem 2 >> Unreliable configuration upon startup • After each power up from a complete power down the system had new seemingly random problems • Believe problems are caused by the EPROMs and FPGAs not being powered on properly • Hardware experts and DCS have worked to develop a sequence of power on to satisfy the hardware requirements • Covered by Stan or other OSU person Rice Workshop PCMB

4. Sasha, “I have a plan for the hardware part of the system. That does not cover the software part. It includes an electrical check of the whole CANbus line and distribution box. The idea is to understand where we lose the signal/power along the CANbus/power line. Another problem is the special power sequence for some PCMBs. I don't know why it happens, and we need to look those PCMBs on the test stand. The "problematic" PCMBs can hang up during a power lose on the CANbus/power line. In this case the PCMBs looks like they are dead. A power cycle is needed to bring them alive.” Rice Workshop PCMB

5. Job Estimation for PCMB • List of jobs from Sasha >> • CANbus testing on the detector: 1/2 day • PCMB distribution box testing on the bench: 1/2 day • This is needed to test the distribution box because the distribution box distributes the power for all PCMBs on the CANbus line. • PCMB distribution box repairing if needed: from 2 days • PCMB investigation regards to power sequence: from 3 days • The goal is to find solution that frees up from power sequence • PCMB repairing and testing if the solution are founded: 3 days (up to 6 days) • If the solution will be found for the "bad" CANbus line we should do  the same for all PCMB of the detector. It takes more than one week. • some additional job can be a setup of several PCMBs on the test stand in ISR, just to emulate the CANbus/power cycle for PCMBs. • Total: 7-12 days • Note that this list can be started immediately, NO power or cooling in the cavern is required. Some (temporary) AC power will be needed in S4F04 for the ATLAS PS crate. Rice Workshop PCMB

6. Summary • What problems were encountered during running? • The PCMBs have experienced problems during operations to date. • Work will be done in Jan-Feb to address these problems • Should be priority project before general power is restored • The job list includes: • Testing of the electrical connections of the bus • Testing of the CANBus itself • Testing of problem PCMB modules on the bench • Working with other CMS persons on ELMB questions • Maintenance Estimate For each module, • We have >6 spare BP, and PCMBs with ELMBs attached • The work schedule was presented > but needs a large contingency Rice Workshop PCMB