INPUT/OUTPUT CARDS OVERVIEW

These I/O cards are implemented in many applications. These cards interface with the process (measurement) signals for the purpose of data acquisition and control. These I/O cards, when assembled into an active or passive backplane, constitute an I/O "controller." The firmware of the "controller" provides for local (ie ladder) logic and for communications with one or more hosts. The controller firmware creates the personality of the unit, be it a Station Computer, PLC, DCS client, or Remote Terminal Unit.

Input signals, to the IOC/RTU, include digital (status), analog, level, quadrature (position), and accumulation (pulsing) type. Output signals, from the IOC/RTU, include digital (controls) and analog (setpoint) types. Digital outputs can be continuous, momentary, or PWM in nature.

These I/O cards organize signals in "groups" (as opposed to "point" oriented controllers), and provides efficient data acquisition for sites requiring medium to large point capacities.

The illustrations of the following page depict the two choices the systems integrator has with regard to field wiring terminations:

1. Type I cards use pull-apart terminal connector(s). The customer's field wiring will terminate on these pull-apart connectors on the respective cardfile assembly. This card type is provided more often than the Type II option as it minimizes the enclosure "real estate" required by Termination Assemblies and/or "marshalling" panels.
2. Type II I/O cards have a minature IDC-type connector. This connector supports ribbon-cable connectors, and is used when separate Termination Assemblies will be implemented.

Most I/O cards are available in either termination configuration, designated by a unique part number version. Both approaches have advantages and disadvantages as summarized in the following table:

ATTRIBUTE                      Type 1                   Type 2                   

                               INTEGRAL TERMINALS       SEPARATE TERMINAL        

                                                        ASS'Y.                   



Cost, including enclosure      less                     more                     

impact                                                                           



Hi-voltage signals             not recommended          preferred                



For minimal enclosure          yes                      no                       

space/size                                                                       



Wire lugs required             no                       no, w/ optional clamps   



Wire lugs accepted             no                       yes                      



Interposing relay assembly     wiring harness (point    ribbon cables            

interconnect                   to point)                                         



Maximum wire guage             14AWG                    12AWG                    

Reminder: Order the corresponding mating termination when specifying the Type I I/O cards.

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I/O CARD SELECTION

Look at picture, side view of a typical cardfile (I/O cards installed in a base/expansion motherboard) mounted in a EIA (19" rack) cabinet. Links to the types of I/O cards available for this unit can be found on the Catalog Introduction Page or from the list below:

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