Westermo LD-64 - Manual (Page 13)

13 6073-2002
Description LD-64
The LD-64 offers redundant fibre optic communication on RS-232/V.24/485/422 in a
multi-drop network. Both multi mode and single mode fibre versions are available. All
fibre optic connections are of the ST-type. Plastic fibre can be used for very short
distances (<20 meters). 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 of up to 25 km can be reached using single mode fibres.
The LD-64 is arranged in a master slave configuration, with the fibre both starting and
finishing at the master unit. Only one master can be configured on a loop at any one
time. There are two F/O channels on each unit, each with a separate transmitter and
receiver. The front cover has 7 LED’s to indicate the state of the various communication
paths.
The LD-64 is equipped with a redundant logic system which will control the flow
of the data under fault conditions. If a break is detected on a fibre or pair of fibres the
data will be re-routed through channel 2, This operation will take approximately 4 ms.
All data in this 4 ms will be lost and will need to be resent.
As with all other Westermo products the LD-64 provides a high level of galvanic
isolation on the power supply side through transformers and also on the alarm sid
through optocouplers. There is no isolation between the RS-232/V.24 and the
RS-485/422 ports as only one port can be used at a time.
Communications standards can be mixed on the same redundant ring. Any device
supporting RS-232/V.24, RS-485 or RS-422 can be connected in the same network
provided they are using the same communications protocols, eg Modbus, Profibus or
Bitbus.
All the operating parameters are set-up via DIP switches located under the lid on the
top of the unit.
Indication and alarm outputs are provided at the master and at the slaves either side
of the fault. The indication and alarm outputs will continue to operate as long as the fault
persists.
The LD-64 is available in a variety of supply voltage in both AC and DC.