Glossary

From MidasWiki
Jump to: navigation, search


Alphabetical Index

A
B
C
D
E
F
G
H
I J K L
M
N
O
P
Q
R
S
T
U
V
W
X Y Z

Glossary

A

Alias Button (Link)
User-created button on the Webserver Status Page providing a symbolic link to any desired ODB location or to an external webpage. Created by user via the /Alias ODB tree.
Application
MIDAS Applications are programs provided by the MIDAS system to perform various functions e.g. data logging, web server etc. They run as MIDAS #Clients.

B

Buffer
MIDAS maintains buffers (i.e. #Shared Memory) for ODB, System Messages, Data, Alarms and History system information. These buffers are managed by the Buffer Manager.

C
Client
A MIDAS Client is an #Application provided by the MIDAS system or (partially) written by the user (e.g. a #Frontend) that links with the MIDAS libraries and runs under the MIDAS system to allow the user to run a MIDAS #Experiment. MIDAS clients can be Local or Remote.
Local
A MIDAS client than runs on the Experiment Host.
Remote
A MIDAS client than runs on a Remote Host.
Custom 
Button (Link) 
User-created button on the Webserver Status Page providing access to a custom page. Custom links are created through the /Custom ODB tree.
Customscript Button

User-created button on a Webserver Custom Page which executes a script when pressed. Created by user via the /Customscript ODB tree.

Page 
User-created Custom Page accessed from the Webserver Status Page. Created when the standard Webserver pages do not fully meet the user's requirements. It usually includes data from the ODB displayed according to the user's preference.

D

Data 
Archiver 
Application Lazylogger can copy the logged data files to another storage device.
Bank 
data in an #Event with a bank header followed by data in a particular data format
Format 
Data Formats "MIDAS" (a variable-length format) and "FIXED" are written by a #Frontend. The format used is determined by the #Equipment List. The data logger can convert MIDAS/FIXED formats to "ROOT" format.
Logger 
Data Logger application mlogger serves multiple purposes related to data logging including logging experimental data to a storage device
Device 
a Hardware module (e.g. a scaler) to be accessed by software called a device driver.
Driver 
Also Device Driver. Software that allows access to a particular hardware module.

E

Environment Variables
Certain Environment Variables are used by MIDAS. Only MIDASSYS is required.
Equipment 
see #Software Equipment
Hardware 
Hardware Devices (e.g. a set of scalers) grouped together for convenience of data readout by a #Software Equipment.
Flag 
Equipment Flags are used in the Equipment Type field in the EQUIPMENT structure of a frontend. The selected flag determines the Equipment Type.
List 
declaration of a #Software Equipment in a Frontend using the EQUIPMENT structure defined in midas.h in the MIDAS package. When the frontend is started, the values in the equipment list for each defined Equipment will be written to the /Equipment ODB tree.
Software 
usually called simply "equipment". A single or a collection of sub-tasks meant to collect and regroup logical or physical data (read from a hardware equipment) under a single and uniquely identified #Event. Each (Software) Equipment is defined using an equipment list in a #Frontend.
ReadOn Flags 
ReadOn Flags are used in the "Read On" field of the equipment declaration to specify when the read-out of an event occurs.
Trigger 
the event is triggered according to the equipment type.
Manual 
A button is created automatically on the Webserver Status Page when an equipment with the equipment flag EQ_MANUAL_TRIGGER is present. A manually-triggered event is sent when button is pressed.
Type 
Equipment Type determined by the equipment flag in the equipment list.
Event 
a collection of data sent into the data stream by a Frontend Equipment, usually in the form of #Data Banks. The Event ID, Event Format, Event Buffer are determined by the #Equipment List for that event.
Format 
see #Data Format
Buffer 
Buffer to contain the events. The event buffer used (usually "SYSTEM") is determined by a parameter in the #Equipment List for that event.
Structure 
Event consists of a header and a data area containing data banks. See Event Structure.
Experiment 
a MIDAS experiment must be defined in order to run the MIDAS DAQ system. It is defined on the Experiment Host and is usually defined in the exptab file, which may define several MIDAS experiment.
Host 
see #Host

F
Frontend 
A MIDAS application built by the user which usually has access to hardware equipment in use by the experiment. Includes Frontend Code linked with a fixed framework mfe.c to form a Frontend. A slow-control frontend is used by the Slow Control System.
Code 
The frontend code is the user-written part of the frontend application (e.g. frontend.c) describing sequence of actions to acquire the hardware data.
Equipment 
See #Software Equipment

H

History
The MIDAS History System records useful information in parallel with the data logging. This can be displayed graphically.
Host
Computer running MIDAS clients, usually #Experiment Host.
Experiment 
the experiment host is the host computer on which the MIDAS experiment #Shared Memory resides.
Remote 
a remote host is a host computer on which (remote) MIDAS client(s) run which connect to the MIDAS experiment on the Experiment Host. See Quickstart Linux to set up a remote host.

M

MSCB
Slow Control Bus can be used for #Slow Control. Optionally can be built into MIDAS DAQ System.

O

ODB
The Online Data Base (ODB) contains all the information needed for an experiment. It can be accessed and/or edited using the ODB Page of the #Web Server or odbedit application.
Directory 
The ODB is structured as a "directory". ODB directory is used as an alternative for ODB tree.
Key 
Data in the ODB are contained in Key/Data pairs in an ODB tree or subtree. ODB Keys can be of various Types. In the Path /Logger/write data, the key is write data.
Type
ODB Key Types can be one of BYTE,CHAR,WORD,SHORT,DWORD,INT,BOOL,FLOAT,DOUBLE,STRING
Data
Data is contained in Key/Data pairs in the ODB. Use the #Web Server or odbedit application to view the Key/Data pairs.
Path 
"address" used to access an ODB Key using the directory structure of the ODB, e.g. /Logger/write data. Upper/Lower Case is ignored.
Subdirectory 
Alternative to ODB Subtree
Subtree 
An ODB subtree starts at a lower level than an ODB Tree, e.g. /Experiment/Security subtree. May also be called a subdirectory.
Tree 
data in the ODB are structured in a tree form with each "directory" dealing with a specific section of the acquisition. An ODB Tree starts at the root level "/", e.g. /Equipment ODB tree. May alternatively be called an ODB directory.

R
Remote host
see#Host
Run
A run starts when the MIDAS system receives a Start transition , and continues until it receives a Stop transition.
State 
MIDAS defines three run states: Stopped, Paused and Running. See Run States and Transitions.

S

Script Button

User-created button on the Webserver Status Page which executes a script when pressed. Created by user via the /Script ODB tree.

Server 
MIDAS 
A remote procedure call (RPC) server mserver available for remote access to a MIDAS experiment.
Web 
See #Web Server
Shared Memory
The MIDAS shared memory regions in RAM are called buffers, and managed by the MIDAS Buffer Manager. MIDAS uses shared memory for the ODB, System Messages, Data buffer, Alarms and History systems.
Saved Files 
The MIDAS shared memory saved files (.*.SHM) for an experiment reside on the Experiment host at the path given by the Environment Variable MIDASSYS.
Slow Control system
Controls and monitors hardware that is not time-critical (e.g. high voltage modules, temperature sensors). See Slow Control System.
State
See #Run State

T

Task
a MIDAS client application. "Task" and "utility" are used in this document as alternatives to "application" by different authors.
Transition
A transition occurs when a MIDAS experiment changes from one run state to another. See Run States and Transitions.

U

Utility
a MIDAS client application. "Utility" and "task" are used in this document as alternatives to application by different authors.

W
Web Server
The MIDAS Web Server is the application mhttpd. It is accessible from a browser and is used to control and monitor a MIDAS experiment.