Communications Document

11Morningstar Product Connectivity Manual
2.2.5 Ethernet Crossover Cable
Similar to a null modem cable, an Ethernet crossover cable allows two devices that are normally
connected through a hub or a router to communicate directly. When these devices are connected
through a hub or router, the crossover is done internally, making a crossover cable unnecessary.
Figure 8. Ethernet Crossover Cable
NOTE: Both standard and crossover Ethernet cables will
vary in color and length. They may look identical on the
outside, but internally they are different.
2.2.6 RJ-11 Cable
RJ-11 cable is the standard cable used in telephone wiring. The wire must be either 4 or 6 (com-
monly referred to as RJ-12) conductor and terminate in RJ-11 connectors. Morningstar products
that require an RJ-11 cable will ship with one in-box. The provided cable should always be used.
Figure 9. RJ-11 (telephone) Cable
2.2.7 Serial / EIA-485 Converter (3rd Party)
As an alternative to the Morningstar RSC-1, other companies offer Serial / EIA-485 converters.
These converters, like the RSC-1 provide the ability to network serial devices over an EIA-485
bus using the MODBUS
TM
protocol. Converters can either be port powered or externally pow-
ered, opto-isolated or non-isolated. For the converter to work properly with Morningstar products,
it must be externally powered and non-isolated. This allows the converter to supply the neces-
sary power to opto-isolated serial ports. Note: The Morningstar RSC-1 adapter is highly recom-