Omron CPM1A operation manual Fcs

	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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