While not strictly necessary, it is easiest to run the event
display if you have two terminal windows open. For example, you need
two windows with a chdr1> prompt. You also need to have your
DISPLAY environment variable set correctly. Check this by typing
echo $DISPLAY. Usually it gives you something like
``hallcxt3.cebaf.gov:0.0'', and if this is the case, you're in good
shape. If it says ``DISPLAY: Undefined variable,'' then you'll have to
type setenv DISPLAY xxx.cebaf.gov:0.0 where xxx is the name of your
terminal (usually written in tape on your monitor).
A. The first step in displaying events is getting them; that is, we
need to start your engine. Nowadays we just type evreplay. Be
sure to use gstart if you have a particular event in mind. If you
want to look at many different particular events, don't worry, we'll
get to that.
(Evreplay is just a short script that modifies your engine a bit to talk to the event display. It sets two ``remote procedure call'' flags. You can do this manually by editing your REPLAY.PARM file; look for the following:
; rpc_on = 1
; rpc_control = 0
just remove the semicolons. All this does is pause the engine, enabling the event display to use "remote procedure calls" to get event information.)
After displaying the usual initial information, you should see
*****************************************************
ENGINE is enabled to receive RPC requests
ENGINE will HANG waiting for RPC requests
If you don't want this to happen, put one of the
following in your CTP setup file
rpc_on = 0 ; Turns off RPC handling
rpc_control = -1 ; No Hanging, but RPC handled
*****************************************************
B. Now go to your other terminal and type evdisplay
from your replay directory. Answer the prompts: tell it whether you
are looking at an offline replay (most likely, thus it's the default)
or online. Next, tell it to choose events manually (default). Enter
the name of the machine your engine is running on It's pretty clever
about figuring this out; most likely you'll take the default. Type
``h'' or ``s'' for HMS or SOS. For this example, type ``s.'' Finally,
hit return because you'd be crazy to run this on anything other than
an xterminal.
That's it. A HIGZ_01@ window should pop up, and your
event display terminal window should have something like the following
prompt:
Run Number = 6143 Event Number = 1
Enter a CTP condition for the next event (?=help,1=any).
:
If it doesn't, go the trouble shooting section. At the first prompt it doesn't have an event to display, so you have to type in a CTP condition. More on that in the next section...
Note that the "?" option will display a list of all the valid commands...