At the system terminal type
The terminal will reply with a message about CAMTST and return a prompt > Give the command....
CAMTST will give a list of all crates that are present and the line that concerns you is the one beginning with BRANCH 4. Crates 1 and 2 both need to be ON. If crates 1 and 2 of branch 4 are not on then recheck that you have the crates on line (Section 2.5). If so then there is a CAMAC fault so get help. If you did happen to leave them off-line then put it on-line and repeat the command STATUS to check that things are OK.
To exit from CAMTST type:
CAMTST will reply " END OF TASK 0 ".