Glossary

 

 

 

FA

Factory automation.

factory computer

A general-purpose computer, usually quite similar to a business computer, that

 

is used in automated factory control.

FAL error

An error generated from the user program by execution of an FAL(06) instruc-

 

tion.

FALS error

An error generated from the user program by execution of an FALS(07) instruc-

 

tion or an error generated by the system.

fatal error

An error that stops PC operation and requires correction before operation can

 

continue.

FCS

See frame checksum.

flag

A dedicated bit in memory that is set by the system to indicate some type of oper-

 

ating status. Some flags, such as the carry flag, can also be set by the operator

 

or via the program.

flicker bit

A bit that is programmed to turn ON and OFF at a specific frequency.

floating-point decimal

A decimal number expressed as a number (the mantissa) multiplied by a power

 

of 10, e.g., 0.538 x 10–5.

force reset

The process of forcibly turning OFF a bit via a programming device. Bits are usu-

 

ally turned OFF as a result of program execution.

force set

The process of forcibly turning ON a bit via a programming device. Bits are usu-

 

ally turned ON as a result of program execution.

forced status

The status of bits that have been force reset or force set.

frame checksum

The results of exclusive ORing all data within a specified calculation range. The

 

frame checksum can be calculated on both the sending and receiving end of a

 

data transfer to confirm that data was transmitted correctly.

function code

A two-digit number used to input an instruction into the PC.

hardware error

An error originating in the hardware structure (electronic components) of the PC,

 

as opposed to a software error, which originates in software (i.e., programs).

header code

A code in an instruction that specifies what the instruction is to do.

hexadecimal

A number system where all numbers are expressed to the base 16. In a PC all

 

data is ultimately stored in binary form, however, displays and inputs on Pro-

 

gramming Devices are often expressed in hexadecimal to simplify operation.

 

Each group of four binary bits is numerically equivalent to one hexadecimal digit.

host computer

A computer that is used to transfer data to or receive data from a PC in a Host

 

Link system. The host computer is used for data management and overall sys-

 

tem control. Host computers are generally small personal or business comput-

 

ers.

host interface

An interface that allows communications with a host computer.

host link

An interface connecting a PC to a host computer to enable monitoring or pro-

 

gram control from the host computer.

HR area

A memory area that preserves bit status during power interrupts and used as

 

work bits in programming.

I/O bit

A bit in memory used to hold I/O status. Input bits reflect the status of input termi-

 

nals; output bits hold the status for output terminals.

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Omron CPM1A operation manual Fcs