Westermo LR-01 - Manual (Page 12)

12 6608-2201
3.3.1 Alarm indications
The units have two alarm outputs marked as CH1 and CH2. When a unit detects a fault
on a fibre optic link the circuit between the contacts “C” and “E” is opened. See section
4.2 for an example how to connect the alarm output to an external relay.
In case of a fault on a fibre link, the receiver on the closest downstream unit will detect
the fault and assert a receive failure alarm. The ring master will also be aware of the fault
and assert the link failure alarm corresponding to the faulty fibre link. In that way a mon-
itoring system only needs to monitor the ring master to obtain the over-all status of the
two fibre links. To find which fibre segment that is broken the alarm status on each unit
must be investigated.
Below are some examples of LR-01 alarm indications when fault is detected on the fibre
link. The break is indicated with a X and an asserted alarm output with a filled circle.
The faults showed in these examples are recovered by the built-in redundancy scheme
within 4 ms. An alarm will remain asserted until the fault is repaired, i.e. when communi-
cation on both fibre links operates normally.
The receiver Rx1 on the ring master unit detects a break on Link 1.
Alarm CH1 is asserted on the ring master unit.
The receiver Rx1 on the rightmost LR-01 unit detects a break on Link 1.
Alarm CH1 is asserted on both local unit and the ring master unit.
Link 1
Link 2
LR-01
CH1
CH2
LR-01
CH1
CH2
LR-01
CH1
CH2
CH1
CH2
LR-01
Ringmaster
x
Link 1
Link 2
LR-01
CH1
CH2
LR-01
CH1
CH2
LR-01
CH1
CH2
CH1
CH2
LR-01
Ringmaster
x