DATCHA
('Demonstrator for ATlas muon CHamber Alignment')
Controls and Alignment
Intro
Control system
Alignment system
 Intro
DATCHA is a test set-up of 3 MDT (Monitored Drift Tubes) muon chambers
(called BIL, BML and BOL),
one of each Layer (Inner, Middle and Outer) of MDTs that will be present
in the Barrel of the
MUON spectrometer of the ATLAS detector.
Photograph of the
DATCHA set-up.
The distances between the chambers in the set-up are comparable to
their final situation when installed in ATLAS.
The main purpose of the test set-up is to study alignment and tracking issues
concerning the combined operation of the chambers as well as the
individual chambers, using cosmic rays.
Look
here for NIKHEF engineering information on DATCHA.
The NIKHEF
CT software engineering group is involved in the controls,
alignment and data acquisition system for DATCHA.
Control system based on CAN-bus
The DATCHA test set-up is used to demonstrate a control system
based on the
CAN industrial fieldbus.
It consists of a CAN network with currently 6 nodes (Nov 1997), hosted by a
SUN workstation (see figure).
Each node contains an 8051-type microcontroller.
The interface between SUN host and CAN-bus is established through a VME-module
with CAN-interface. A GUI and several task-specific tools enable the user
to monitor and control the system via simple typed commands and mouse-clicks.
The control system is used to:
- - set read-out thresholds
- - disable individual read-out channels
- - generate calibration triggers
- - set and monitor high-voltage powersupplies
- - monitor electronics temperatures
- - monitor chamber temperatures
Documentation on the DATCHA control system:
-
a Figure (PostScript) showing
the current status of the DATCHA control system's CAN node and device
configuration.
-
Specifications of the
DATCHA control system (needs update).
-
"DATCHA Controls"
- a User Manual for the current DATCHA control system.
(also available in PostScript)
-
"GPCAN, a general purpose CAN-bus node"
- a Reference and User Manual describing the 'GPCAN' hardware and
software running
on the 'GPCAN' CAN-nodes used in DATCHA.
(also available in PostScript)
-
"Crystal-CAN, a CAN-bus node for monitoring multiple distributed analog
channels"
- a Reference and User Manual describing the software running
on prototype CAN-nodes with high-precision ADCs for controlling and monitoring
temperature sensors (up to 240 per node) and B-field sensors
(up to 8 per node).
in DATCHA 90 temperature sensors (30 per MDT chamber;
added to the system: Nov 1997) and a few B-field sensors (ca. Jan 1998)
(for demonstration purposes, since there is no B-field
present at DATCHA...) are added to the DATCHA control system.
(also available in PostScript)
Pictures of Crystal-CAN node and
Temperature sensor boards
Related documents:
-
"A CAN-based Control System for DATCHA"
- a working document describing DATCHA
host control implementation issues and tools used while developing
software for the 'GPCAN' CAN-node.
(also available in PostScript)
-
"CANDIDE, a fieldbus system to control detector front-end electronics"
- (available in PDF or
Postscript)
an article about the usage of CAN-bus in a detector control system presented
at the
ICALEPCS-95 Conference
RASNIK alignment system
The DATCHA setup is primarily meant to test the
RASNIK alignment system. The
ICARAS software to control and readout the
alignment instrumentation is implemented on a Pentium PC running Windows95,
using the Visual C++ development environment.
Wim Heubers
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