Rockwell Automation 1764-xxxx MICROLOGIX 1500 PROGRAMMABLE CONTROLLERS - Manual (Page 160)

Publication 1764-UM001B-EN-P - April 2002
Glossary 4
half-duplex
A mode of communication where data transmission is limited to one
direction at a time.
hard disk
A storage device in a personal computer.
high byte
Bits 8 to 15 of a word.
housekeeping
The portion of the scan when the controller performs internal checks
and services communications.
input device
A device, such as a push button or a switch, that supplies an electrical
signal to the controller.
input scan
The controller reads all input devices connected to the input
terminals.
inrush current
The temporary surge of current produced when a device or circuit is
initially energized.
instruction
A mnemonic defining an operation to be performed by the processor.
A rung in a program consists of a set of input and output instructions.
The input instructions are evaluated by the controller as being true or
false. In turn, the controller sets the output instructions to true or false.
instruction set
The set of instructions available within a controller.
I/O
Input and Output