The Camac 204 module and its companion PCI chassis offers the ability to 
monitor up to 64 analog channels and 32 digital channels. Each channel 
has its own settable analog or digital limits, by which a comparison of
the realtime value is made. The 204 arrangement makes use of user 
defined tables which are driven by decoded clock events. At the end of a 
defined table, a comparison is performed of all unmasked channels which
are associated with that table. Unmasked channels that are found to be 
outside the specified limits, causes the 204 module to 'trip'. A list of 
the tripped channels that caused the module to trip can then be displayed. 
204 modules have a single 'permit' output that can be connected to a 200 
module beam permit input panel. In this way, the beam permit for a machine 
or beamline may be dropped if any channel is found to be outside of its 
acceptable range when the comparison is made.