Westermo LD-64D HV Manuel D'installation page 13

Functional description LD-64D
LD-64D offers redundant fibre optic communication between equipment with RS-485
interface. The unit is specially developed for two wire RS-485 protocols using 9 position
D-sub for connection to the network. Possibility to connect to a 9-position screw
block is also available.
The fibre optic interface uses ST-connectors and both multi mode and single mode
fibre versions are available. The maximum transmission distance is calculated from
the available power budget of the modems and the attenuation of the cable, splice
joints and connectors. Distances up to 25 km can be reached using single mode fibres.
The LD-64D units are used in a ring connection and one unit is configured via switches
as the master. The redundant logical system will control the flow of the data during fault
conditions. If a break is detected on a fibre or pair of fibres the data will be re-routed.
This operation will take approximately 4 ms and all data transmitted during this period
will be lost and will need to be resent.
The unit has indications for dataflow and also fault alarm outputs for each fibre optical
channel which for example can control an external relay. The alarm outputs will be
activated as long as the fault persists.
As with all other Westermo products the LD-64D provides a high level of galvanic
isolation on the power supply side through transformers and also on the alarm side
through optocouplers.
LD-64D can be used at all standard transmission speeds up to 375 kbit/s and all
operating parameters are set-up via DIP switches easily accessable under the lid on
the top of each unit.
LD-64D is available in low (LV) and high voltage (HV) versions. LD-64D LV supports
power supplies 12–45 V AC ± 5% and 12–55 V DC ±5%. LD-64D HV supports power
supplies 95–240 V AC ±5% and 110–240 V DC ± 5%.
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