TB 11/06/02

Trouble shooting camac problems
==================================

It seems that we have had too many problems with the camac trigger 
recently. One of the things you may need to do is to check that all 
bits are transferred through the camac data-way (branch highway cables)

This can be done in the counting bay. Each camac crate (1, 2) has a 24-bit 
output register to which you can write and read. These registers are in 
slots 23 and 22, respectively. If all bits are fine, the camac connection 
should be good.

The program to use is cnaf. It returns the q,x status bits. These
should always return equal to 1


What you need to do
====================

from dblast07:

> source ~/commis/coda/coda_user.setup


> cnaf blrocv1 1 23 0 0

(reads address zero of module 23 in crate 1)

> cnaf blrocv1 1 23 16 16777215

(writes number 2^24 -1 to address zero)

> cnaf blrocv1 1 23 0 0  	(read back, should be the last number you wrote)



For crate 2 (beam left) you can do something similar


> cnaf blrocv1 2 22 0 0

> cnaf blrocv1 2 22 16 16777215

> cnaf blrocv1 2 22 0 0  	


if you always receive q=1 and x=1, the dataway is fine. If you are
in the D-tunnel, you will see red lights turn on/off in the above modules.


Example:

<blast@dblast07:113> cnaf blrocv1 2 22 0 0
dec:0    hex:0    q:1  x:1
<blast@dblast07:114> cnaf blrocv1 1 23 0 16 16777215
q:1  x:1
<blast@dblast07:115> cnaf blrocv1 2 22 0 0
dec:0    hex:0    q:1  x:1
<blast@dblast07:116> cnaf blrocv1 1 23 0 0
dec:16777215    hex:ffffff    q:1  x:1
<blast@dblast07:117> cnaf blrocv1 1 23 0 16 0
q:1  x:1
<blast@dblast07:118> cnaf blrocv1 1 23 0 0
dec:0    hex:0    q:1  x:1


What to do if something is wrong
=================================


If you don't get q:1, x:1 there is a problem with camac. 


_ Call for help....


.... or try to fix it yourself (you have to be patient)


_ Resetting the crate controllers

Go to D-tunnel.  Put crates 1 & 2 offline (there is a switch). Turn them off.
Wait a few seconds. Turn them back on.  Toggle clear (c) and reset (z) (it is 
another switch).  Hit the (small) white reset button on the camac controller in 
the VME crate (that is that VME module where the gray branch-highway cable ends).
Bring crate 1 and then 2 back online (one at a time). Hit again reset on the
VME camac controller.

Test again with the cnaf commands. *NOTE* you will have to redownload the trigger
to restart data taking.

_ Sometimes resetting the crates once is not enough. You may need to give more
  resets and clear (remember, only when crate is "offline") but you should not
  power-cycle too much as that is in principle needed once and is a dangerous
  operation. If problems persist, you may have to disconnect/reconnect the BHWY
  cables. Do that gently and when all crates are offline. The BHWY do not need 
  to be squeezed in very tightly (that can also be a cause of problems).