I-o-display-systems Basic I/O Product Manual de usuario descargar pdf (Pagina 57)

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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I-o-display-systems Basic I/O Product Manual de usuario Pagina 57