User guide

Troubleshooting
System Description, AutroSafe Integrated Fire & Gas Detection System, 116-P-ASAFE-IFG/XE Rev. B, 2005-10-27,
Autronica Fire and Security AS
Page 71
8. Troubleshooting
8.1.1 BSD-321 / EAU-341
Problem / Situation / Fault
message
Possible Cause Action
Point Not responding.
• The wrong protocol has been
used for a detector.
The system is sensitive to
external noise / interference
when, for example, lights are
switched on or thermostats
are activated.
• Missing reference to RS-485
• Break on one of the wires
• The RS-485 cable is too long
(exceeds the maximum
length).
Only short messages are
transmitted.
• During initialisation a great
number of messages are
transmitted. Faults tend to
occur more frequently.
During normal operation the
system will be more stable.
Earth fault of AFB leads to
communication faults.
• Erronous pair connection,
somewhere the CT
(CT=name?) and on of the
pair wires have been
swapped. This may work
fine, but damages
communication in the event
of an Earth fault.
AFB earthing and shielding: In a
system that includes several AFB
units, there are several options to
achieve proper Earthing, and also to
include earth fault detection. It is
important to keep in mind the various
references, sense input etc. For
example, a EAU-341 is defined to
sense earth faults of AFB. The shield
of the AFB is tied to Earth, but the
Center tap (CT) is tied to the Earth
fault sense input. Out somewhere at
the AFB loop a BSD-321 has tied the
CT to Shield, which together make an
earth fault. Isolated, per product, this is
allowed as a proper installation, but not
at a system view. See “System
Shielding and Earthing” chapter
5.6,
for further directions.