| 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. |