BNMR: Scripts

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A number of important scripts are used in the bnmr and bnqr experiments. Some of the most important are described here. Unless otherwise noted, the scripts described here can be found in directory ~/online/<beamline>/bin.


This important script in $HOME is the bash script executed on log in. This sets up the path, the aliases and environment variables required for running the DAQ system. This file is shared by all the machines in the NIS cluster with isdaq00 as master. This includes isdaq01, isdaq06, lxbnmr, lxbnqr. This script therefore checks the $HOST environment variable before setting up the DAQ system. See BNMR: Experimental Setup for details.

Scripts to restart MIDAS clients

A number of scripts are provided to start or restart the MIDAS clients needed for the data acquisition system. The most important of these is start-all which starts any missing clients. Scripts are also provided to start individual clients. These scripts are usually accessed from the Programs page when the user presses the restart button.

A script kill-all is provided to shut down all the clients.


start-all is an alias to the script start-all-daq-bn[mq]r (see Nomenclature). This script is run by the experimenter to start all the MIDAS clients needed for the DAQ system. It checks to see if each client is already running, and if not, starts it either by calling another script, or directly. It can be run at any time during the run to restart missing clients.


kill-all is an alias to the script kill-all. This script kills all DAQ related clients. When there is some problem with the DAQ that cannot be otherwise resolved, users often do a kill-all followed by a start-all to ensure a clean restart.


The script start_frontend must be run on the VMIC (not the host computer). It is may be run directly, but is usually called by the script start-all. It starts the frontend program for bnmr or bnqr experiment under the screen program (see show-windows).


The script start_mdarc is run when the Programs page button restart for client bnxr_logger is pressed. This script is run on the host computer. This script restarts the MUD logger under the screen program (see show-windows).

Script to show screen program windows


show-windows is an alias to the script show-windows. This script attaches to and displays (in an xterm, if possible) one or all midas clients that were started and managed under the screen program. This includes clients mdarc,mheader and the frontend (client name febn[mq]r_vmic - see Nomenclature).

The advantage of the screen program is that the terminal does not disappear when the client fails. Also it can be accessed from another terminal, and killing the window does not kill the client.

Previously each of these clients was started in an xterm by start-all, so that progress could be monitored, and any errors :displayed. The xterms appeared on the screen where start-all was executed, and were inaccessible to any other terminal. If the
client failed, the xterm promptly disappeared, so only the error messages sent to the MIDAS logger could be read.

  • To display all windows, give no argument, or the word "all".
  • To display a specific window, give the parameter in Table 1 :
Table 1 show-windows parameters
Command Parameter Action
show-windows to show all windows
show-windows all
show-windows vmic to show frontend window
show-windows frontend

Run transition scripts

Midas has a feature where programs can be automatically run at the start/end of each run (see the /Programs ODB tree documentation).

For bnmr and bnqr we only define an end-of-run program. All logic for the start of run is handled by clients that are always running.

End of run -

The /Programs/Execute on stop run is set to run the python program bnxr_common/ This program reads the /Experiment/Edit on start parameters (i.e. the parameters entered by the experimenter on starting a run), other ODB parameters including the Experimental (PPG) Mode of the run and whether it is run in dual or single channel mode, reads the statistics of the CAMP logged devices, and sends them all to the appropriate elog bnmr or bnqr. Automatic elog entries are identified in the Elog by the Type ("Automatic Elog"). The System parameter is set to the PPG Mode of the run.