We have discovered that when phantom panels suddenly appear on a bus with no explanation the dominating factor has been that their cat-5 is BAD, it has been found that either a CONNECTION is LOOSE or a BROKEN WIRE in the CAT-5.
The Clock or if the clock is not present, a relay board, must ALWAYs “Master the bus” so that there is an orderly exchange of information. If a relay panel cannot see the clock it will try to take over the bus and become the master for its section. Once it is mastering it asks the switches “Who wants an update?” The first switch says “What is the status of my relay?” (So I can keep the LED current.)
The reply is a signal that exactly matches the correct signal in answer to the clock saying “Has a Clock Display button been pushed.”
If the clock loses connection with other relay panels because we have and intermittent break in the bus, then one of the relay panels in that section will start to master and just at the point the switches start asking questions, the bus get reconnected, the answer is sent to and received by the clock which takes it as a Display Button push. The bus opens again and the cycle repeats.
There is no software fix for this situation. Instead we use this situation to tell us if the bus is OK.
What we have learnt.
1) The Bus can pass its FAC and a scope test with flying colors, but still have and intermittent problem. The only way to be certain the bus is OK is to Zero the errors and check the error count at least 24 hours later. If the error count is up in the thousands we have an intermittent connection and the bus must be re-checked from end to end.
2) It is possible that the EZ RJ-45s we are now promoting are harder to get into the jack if the ends of the wires have not been cut off properly. Insist that your installers hear the click as the connector goes into the jack.
Vantis 130: A switch was found to have lose RJ-45 cable, when the switch was taken out of the wall the cat-5 fell out of the switch. When the cat-5 was connected properly the bus stabilized and no more phantom panels.
Guardian Building Products: LCP-13 had an RJ-45 that was not pushed home into the socket, furthermore that socket had “flattened” spring connections in the jack. Inspection of the RJ-45 showed that the crimps had not been pushed all the way into the connector and were only just below the level of the plastic dividers. This made it hard to push the connector in and make it click and the jack was. The board had to be replaced. At least 12 other RJ-45s were replaced on this bus as being substandard connections. The bus is stable.
Fire station 10: This job had phantom panels and the cause was found to be a broken wire in the cat-5, the lack of a terminator and several other bad connections. Once all of these problems were fixed the bus became solid.
We have document 3 other sites that were developing self-generated phantom panels and in each case the cause has been attributed to a bad cat-5 bus.
A solid cat-5 bus is mandatory for system and you must insist that the EC correct a deficient bus.