If you want to look at the history of variables from the past, you can
either

- from Netscape, select MIDAS status page
     select History
       select the appropriate panel
          select button Query (on the righthand side) 
            set the Start date and Stop date
              select Query

- from any window on computer midtwist, type stripchart
  This is a gui and there is documentation by pressing help
  on the bottom menu bar. 
  
  Here is a simple example:
   Select Mhist menu, 
      select "Set history-file path" and set to 
            /data7/elog_history
      select "Open old history file" and select the start date
           ie 011102.hst  --> yymmdd --> 2 nov 2001
         select the event  (ie Gas)
            select the time units, period and interval 
            select the variables (ie, D1_Flow, D7_Flow)
            press OK
      select "detail-all" or "detail-single" if you want to see/modify
          scale, zoom, hardcopy, etc.

The program stripchart is maintained by Gertjan Hoffman, postdoc for 
Chaos. He welcomes comments, bug reports, etc. and he is very responsive
to fix problems:  gertjan@triumf.ca 

=====

If you want to make plots of variables in the history lists in a
format other than is offered by the History button on the status
page (e.g., to plot data for some interval some days ago, to
control your offsets, plotting characteristics, etc.) you can
retrieve the data from the midas history files with the mhist command.

On the midas computer (e.g., midtwist), cd to data directory (e.g.,
/data_onl/2001) and use the mhist command. If you just type
mhist, you get to select from a list of choices the event ID,
such as

Available events:
ID 30: System
ID 17: Solenoid
ID 16: DAQ
ID 12: Chamber
ID 13: u_Beam
ID 14: HV
ID 19: Scalers
ID 15: p_Beam
ID 11: Gas
ID 10: PostAmp

You can then similarly select the variable(s) to list, how many
hours to list the variable(s) for, and the minimum interval in
seconds to list. This will put the data out to your screen. Be
careful in your hours and interval selection or you may get a lot
of text on your window. You can cut and paste this text to a file
on another computer for plotting or analysis.

For plotting or analysis of larger amounts of data  with other
programs such as physica, there is a better way, once you have
found your event ID and variable name(s). The options are listed
with the command "mhist -h" or in the midas help files. For
example, to display the value of the camac scaler Scaler_0 in one
minute intervals, starting at 9:00 am and ending at 9:10 am
November 25, use the command

mhist -e 19 -v Scaler_0 -t 60 -s 011125.0900 -p 011125.0910 > ~/mydata.txt

This will put the following data into mydata.txt in your home
directory.

Nov 25 09:00:19 2001	2480
Nov 25 09:01:19 2001	2385
Nov 25 09:02:19 2001	2520
Nov 25 09:03:19 2001	2316
Nov 25 09:04:20 2001	2554
Nov 25 09:05:21 2001	2837
Nov 25 09:06:21 2001	2401
Nov 25 09:08:01 2001	2491
Nov 25 09:09:01 2001	2528

You can then copy this file to wherever you wish, deleting the
one left behind.