Chapter 11 Troubleshooting
208 BMTW-SVN01F-EN
BCU Locks Up
This is a more specific symptom of a BCU that is not responding. In this
situation the BCU works most of the time but periodically locks ups and
stops responding. The following list describes situations that could cause
this problem and suggests solutions:
• A building power disturbance, such as that caused by electrical
storms, may affect BCU power in such a way that the BCU locks up.
Cycling power again on the BCU will normally clear this up. Repeat
occurrences of this type of problem would warrant installation of an
external device that protects against ac-power transients.
• If the BCU has a modem installed, a power disturbance can enter
through the modem line. Cycling BCU power will normally resolve
this problem. Repeat occurrences of this type of problem warrant
installation of an in-line, modem-line transient protection device.
• Strong EMI/RFI interference can lock up a BCU. Avoid using cell
phones and walkie-talkies within 6 ft of a BCU (unless the cell phone
is being used as a modem connection device for accessing the BCU).
• Programming the BCU (from a Tracer Summit PC Workstation) with
too many UCM and program objects can overload a BCU so that, dur-
ing periods of high activity, the BCU is not able to complete all tasks
and goes into a “Watch Dog Timeout” sequence. To avoid this prob-
lem, make sure to estimate the BCU memory usage with the BCU siz-
ing spreadsheet before connecting UCMs and programming the BCU.
As a rule of thumb, leave at least 15% memory headroom.
• BCUs that are programmed to route alarms/events to remote Tracer
Summit PC Workstations will lock up over time if the remote work-
station is not available to receive dialed out alarms or is not con-
nected periodically to harvest the alarms. Generally, this problem is
most prevalent when the BCU has been programmed to route alarms/
events to multiple remote PC Workstations that are not available to
receive or harvest the alarms frequently enough.
• Defective ARCNET, Ethernet, hub cards, and modems can cause the
BCU to lock up.
BCU Does Not Communicate Via
Modem
BCU modem communication problems fall into two general categories:
• Problems with the modem and phone line
• Problems with the BCU programming setup
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