Hand-Held Programmers of PLCs 280

advisory message

A message following the error code that helps you quickly identify the error. On a MicroLogix HHP, the error code 0001 is followed by the advisory message HARDWARE FAILURE.

alphanumeric key

A key on a hand-held programmer that contains numerals 0 through 9 or letters A through Z. These keys allow you to enter values and characters into a program.

anti-static wrist strap

A device worn on the wrist that grounds a person and prevents the buildup of static electricity on the body.

central processing unit

CPU. The microprocessor device inside a computer that controls system activities. The central processing unit executes a PLC program and performs all logic activities for the system.

communication cable

The physical channel by which data travels through a network. A communication cable allows the HHP to interface directly with the PLC.

configure

To arrange the settings for a piece of equipment or software.

cursor

A blinking character on a display screen that indicates the current input location.

D2-HPP

A model of hand-held programmer manufactured by AutomationDirect.

debug

To identify and remove errors from a PLC.

diagnostics

A set of computer instructions that investigates or analyzes the cause or nature of errors or failures in the PLC.

display screen

The area on a hand-held programmer that allows you to view programs, menu items, and messages.

download

To transfer data from another device to your device. Hand-held programmers can download information from a PLC.

dumb terminal

A hand-held programmer that simply acts as keyboard and monitor for the PLC. Dumb terminals have no intelligence or memory of their own.

editing key

A key on a hand-held programmer that allows you to make changes to data in the HHP.

electrostatic discharge

A release of static electricity that can potentially cause injury or damage components.

error log

A file in the memory of the CPU that tracks errors and failures encountered by the PLC system.

error message

A warning displayed on the HHP screen that alerts you to a problem with the PLC system.

hand-held programmer

HHP. A PLC programming device that combines a display screen and keypad all in one unit. Hand-held programmers are also known as hand-held terminals and have specially assigned keys that allow you to enter program instructions, make changes, and navigate and troubleshoot the PLC system.

hand-held terminal

A PLC programming device that combines a display screen and keypad all in one unit. Hand-held terminals are also known as hand-held programmers and have specially assigned keys that allow you to enter program instructions, make changes, and navigate and troubleshoot the PLC system.

hardware

The physical components that form a PLC hand-held programmer.

instruction key

A key on a hand-held programmer that allows you to select and enter instructions.

instruction list

A low-level, textual PLC programming language that uses compact code. Instruction lists use mnemonic codes as a substitute for more traditional ladder diagrams.

interface

A hardware configuration that connects devices for the purpose of network communication.

keypad

A set of buttons used for entering information and instructions into a hand-held programmer.

ladder diagram

A representation of a ladder logic program that uses symbols to represent the on or off status of input/output devices.

LCD screen

Liquid crystal display screen. The area on a hand-held programmer that allows you to view programs, menu items, and messages.

LED

Light emitting diode. A semiconductor device that emits a narrow spectrum of light in a forward direction.

memory

The portion of a computer where data is stored.

memory card

A storage device that allows data to be easily read and easily changed. Memory cards continue to store data if the power source is removed.

memory chip

An integrated circuit that stores data.

mnemonic

A symbol or expression that is easy to remember and represents a longer form of something else. Mnemonics are used in HHP instruction lists.

mode

One of a number of possible settings used by a hand-held programmer to run certain operations such as programming or testing.

navigation key

A key on a hand-held programmer that allows you to scroll up, down, and sideways on the display screen.

offline

An operational mode in which a PLC is not accepting inputs.

online

An operational mode in which a PLC is connected to the system network and ready to accept inputs.

operation key

A key on a hand-held programmer that allows you to perform different tasks such as configuration and diagnostics.

overwrite

To erase existing data by replacing it with new data.

personal computer

PC. A processor-driven device for an individual user and commercial software. A personal computer may be used as a programming device for a PLC.

processor

The main device that reads and interprets information and then carries out instructions.

program mode

A CPU operating mode that is active when loading program instructions into the CPU or when editing an existing program. During program mode, the CPU does not run a program or perform the operating cycle.

programmable logic controller

PLC. A processor-driven device that uses logic-based software to provide electrical control to machines and devices.

RS-232

An older but standard type of communication cable used for connecting peripheral devices to a computer.

RS-442

A communication cable that transmits data at faster rates and over longer distances than RS-232. However, RS-442 is not commonly used.

run mode

A CPU operating mode that is active when the CPU is executing the steps of a program. Run mode is required to energize outputs.

rung

A horizontal line in a PLC ladder diagram that contains program instructions.

sequence

The order in which keys are pressed. Key sequences are used to issue commands and instructions.

smart terminal

A hand-held programmer that can store programs and function independent of a PLC. Smart terminals are also called stand-alone terminals.

software

The programs and instructions that a processor-driven device carries out.

stand-alone terminal

A hand-held programmer that can store programs and function independent of a PLC. Stand-alone terminals are also called smart terminals.

test mode

An operating mode that allows a CPU to run a program without energizing output devices. Test mode may be used to check for program errors.

upload

To transfer data from your device to another device. Hand-held programmers can upload information to a PLC.

user manual

A document created by the manufacturer of a device that provides detailed installation and operation instructions.