Installation 2 – I-O Display Systems Basic I/O Product User Manual

Page 57

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Installation 2

2-3(Vol.2)

Designing the Network

In order for the BASIC I/O AD to share its data with the host computer, it must be linked via
a serial connection. This link can be hard-wired using an RS-422 dual twisted pair or an RS-
485 single twisted pair connection where the wire run between devices is less than 5000 feet.
In any event, the appropriate transmitter of the BASIC I/O AD will be connected to a suitable
receiver of the host computer. Multiple BASIC I/O AD chassis can be networked together to
service large numbers of I/O points. These serial connections can be either multidrop or
repeat.

Multidrop:

Multidrop networks can be up to 5000 ft long end-to-end.

Each station is passively located on the network and represents one “Drop” or
load to the host communication driver.

A multidrop network will tolerate loss of power to any one station without
effecting the rest of the network.
RS-485 can only be multidrop
Signal boost may be necessary depending on line conditions and number of
drops.

Repeat:

Repeat networks can be as long as 5000 ft between each unit.

Each station plays an active role in communications to other units. If power is
removed from a unit in a repeat network, communications to units “downstream”
from it will be lost as well.

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