TWEPP 2015 - Topical Workshop on Electronics for Particle Physics

Preparing the hardware of the CMS Electromagnetic Calorimeter control and safety systems for LHC Run 2

Sep 30, 2015, 5:01 PM

1m

Hall of Civil Engineering (Lisbon)

Poster Systems Poster

Speaker

Oliver Holme (ETH Zurich (CH))

Description

The Detector Control System (DCS) of the CMS Electromagnetic Calorimeter (ECAL) has undergone significant improvements during the first LHC Long Shutdown (LS1). Based on the experience acquired during the first period of physics data taking of the LHC, several hardware projects were carried out to improve data accuracy, to minimise the impact of failures and to extend remote control possibilities in order to accelerate recovery from problematic situations. This paper outlines the hardware of the CMS ECAL DCS and safety systems and explains in detail the requirements, design and commissioning of the new hardware projects.

Summary

The CMS ECAL DCS consists of the following dedicated hardware systems to monitor the environmental conditions in the detector volume:

• Precision temperature monitoring based on ELMBs (Embedded Local
  Monitor Boards)
• Humidity monitoring based on PIC microcontrollers

In addition, interfaces to other hardware systems are available to provide both monitoring and control of:

• Low voltage power supplies based on CAEN and Wiener commercial
  hardware
• High voltage power supplies based on CAEN commercial
  hardware
• Safety systems based on Siemens PLCs

The upgrade projects to be described in this paper are the following:

1. A new microcontroller based relative humidity readout system
   which overcomes issues imposed by long cable lengths, previously
   limiting the readout range to 60 - 80%. The new PIC microcontroller
   based hardware design extends this range to 10 - 80%. The MODBUS
   communication protocol was chosen to ease the integration with the
   existing control system software. Commercial RS485-to-Ethernet
   adapters are used to allow remote monitoring using MODBUS over TCP.

2. A system for remotely rebooting commercial power supplies from
   CAEN. These power supplies occasionally need rebooting in order to
   exit a problematic situation. Previously this involved an
   intervention at the CMS experiment site, which could take around one
   hour if no expert was on site at the time. The power supplies can be
   rebooted via a digital signal to an input on the mainframe front
   panel. A custom hardware solution, based on the Arduino platform,
   was designed to generate the necessary digital signals to trigger
   the mainframe reboot. To facilitate the integration into the
   controls software, the MODBUS over TCP protocol was implemented in
   the microcontroller.

3. An improved power distribution system was designed for the CMS
   ECAL precision temperature monitoring system. This upgrade was
   motivated by observations that a single readout board failure could
   degrade the whole monitoring system. To overcome this issue, a new
   power distribution with greater granularity and individually
   switched power lines was designed. In addition, the ability to
   switch individual power lines is advantageous for locating and
   isolating a fault.

These systems are fully tested, commissioned and integrated in the CMS ECAL DCS.

Presentation materials

Poster_174.pdf