Omron SYSMAC C200H, Руководство по эксплуатации

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Glossary
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cial purposes, such as holding the status input from external devices, while
other bits are available for general use in programming.
bit address The location in memory where a bit of data is stored. A bit address must
specify (sometimes by default) the data area and word that is being ad-
dressed, as well as the number of the bit.
bit designator An operand that is used to designate the bit or bits of a word to be used by
an instruction.
bit number A number that indicates the location of a bit within a word. Bit 00 is the right-
most (least-significant) bit; bit 15 is the leftmost (most-significant) bit.
buffer A temporary storage space for data in a computerized device.
building-block PC A PC that is constructed from individual components, or “building blocks.”
With building-block PCs, there is no one Unit that is independently identifi-
able as a PC. The PC is rather a functional assembly of components.
bus bar The line leading down the left and sometimes right side of a ladder diagram.
Instruction execution proceeds down the bus bar, which is the starting point
for all instruction lines.
call A process by which instruction execution shifts from the main program to a
subroutine. The subroutine may be called by an instruction or by an interrupt.
carry flag A flag that is used with arithmetic operations to hold a carry from an addition
or multiplication operation, or to indicate that the result is negative in a sub-
traction operation. The carry flag is also used with certain types of shift oper-
ations.
clock pulse A pulse available at a certain bit in memory for use in timing operations. Vari-
ous clock pulses are available with different pulse widths.
clock pulse bit A bit in memory that supplies a pulse that can be used to time operations.
Various clock pulse bits are available with different pulse widths, and there-
fore different frequencies.
common data Data that is stored in the LR Area of a PC and which is shared by other PCs
in the same the same system. Each PC has a specified section of the LR
Area allocated to it. This allocation is the same in each LR Area of each PC.
condition An message placed in an instruction line to direct the way in which the termi-
nal instructions, on the right side, are to be executed. Each condition is as-
signed to a bit in memory that determines its status. The status of the bit as-
signed to each condition determines, in turn, the execution condition for each
instruction up to a terminal instruction on the right side of the ladder diagram.
constant An operand for which the actual numeric value is specified by the user, and
which is then stored in a particular address in the data memory.
control bit A bit in a memory area that is set either through the program or via a Pro-
gramming Device to achieve a specific purpose, e.g., a Restart bit is turned
ON and OFF to restart a Unit.