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:
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.
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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