Speaker
Description
The Large Hadron Collider at CERN restarted in 2015 with a higher
centre-of-mass energy of 13 TeV. The instantaneous luminosity is expected
to increase significantly in the coming
years. An upgraded Level-1 trigger system is being deployed in the CMS
experiment in order to maintain the same efficiencies for searches and
precision measurements as those achieved in
the previous run. This system must be controlled and monitored coherently
through software, with high operational efficiency.
The legacy system is composed of approximately 4000 data processor boards,
of several custom application-specific designs. These boards are organised
into several subsystems; each
subsystem receives data from different detector systems (calorimeters,
barrel/endcap muon detectors), or with differing granularity. These boards
have been controlled and monitored by a
medium-sized distributed system of over 40 computers and 200 processes.
Only a small fraction of the control and monitoring software was common
between the different subsystems; the
configuration data was stored in a database, with a different schema for
each subsystem. This large proportion of subsystem-specific software
resulted in high long-term maintenance
costs, and a high risk of losing critical knowledge through the turnover
of software developers in the Level-1 trigger project.
The upgraded system is composed of a set of general purpose boards, that
follow the MicroTCA specification, and transmit data over optical links,
resulting in a more homogeneous system.
This system will contain the order of 100 boards connected by 3000 optical
links, which must be controlled and monitored coherently. The associated
software is based on generic C++
classes corresponding to the firmware blocks that are shared across
different cards, regardless of the role that the card plays in the system.
A common database schema will also be used
to describe the hardware composition and configuration data. Whilst
providing a generic description of the upgrade hardware, its monitoring
data, and control interface, this software
framework (SWATCH) must also have the flexibility to allow each subsystem
to specify different configuration sequences and monitoring data depending
on its role. By increasing the
proportion of common software, the upgrade system's software will require
less manpower for development and maintenance. By defining a generic
hardware description of significantly
finer granularity, the SWATCH framework will be able to provide a more
uniform graphical interface across the different subsystems compared with
the legacy system, simplifying the
training of the shift crew, on-call experts, and other operation
personnel.
We present here, the design of the control software for the upgrade
Level-1 Trigger, and experience from using this software to commission the
upgraded system.
| Primary Keyword (Mandatory) | Trigger |
|---|---|
| Secondary Keyword (Optional) | DAQ |
| Tertiary Keyword (Optional) | Control systems |
