Disaster Strikes

Disaster is usually signalled by a message in the di window that the run is ending due to an error. Usually, the exact error is not known to the Master SSP, because the problem occurred in some secondary SSP when it was under the control of the Trigger SSP.

To diagnose the problem, do the following things, in order of easiest to hardest:

• Make sure all FASTBUS crates have power.

• Look at the SSP's using the sspar and sspcheck software. See the section below on using these programs.

• Look at the cable segment display board in the master crate for bits stuck on.

• Measure the cable segment differential voltages using the switch box and DVM.

• As a a last resort, disassemble the cable segment to do a binary search for the SSP causing the problem. If you get to this point, you're in for several hours of work, so be absolutely certain that you need to do this.