Impulse 463N Manuale Utente Scaricare il pdf (Pagina 52)

©Sealevel Systems, Inc.

SL9049 - 11/2010

SeaI/O Manual

A “stack” or “chain” of SeaI/O modules, connected via the pass-through connectors or screw

terminals on the left side of the enclosure, communicates via an RS-485 bus, which must be

properly terminated to work correctly. A set of three dipswitches is located on the left side of

enclosure, next to the “ADDR” rotary switch. These switches control line termination and the RS-485

pull-up and pull-down resistors.

The pull-up and pull-down resistors ensure that the input ports are at a known state when not

being driven by the RS-485 line. In most cases, all three of the dipswitches on each SeaI/O module

should be in the down position, except the two end modules. The first and last SeaI/O modules in

the chain should have all three dipswitches in the up (enabled) position.

Make sure that only the first and last SeaI/O modules have line termination enabled (up

position). Improper termination settings can result in invalid data or communication

failures.

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Impulse 463N Manuale Utente Pagina 52