I-O Display Systems Basic I/O Product manual Designing the Network, Multidrop

Installation 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

aserial 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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