4-4SectionAR Area
60
Word(s) Read/
write
FunctionBit(s)
SR 254 00 1-minute clock pulse (30 seconds ON; 30 seconds OFF) Read-
01 0.02-second clock pulse (0.01 second ON; 0.01 second OFF) only
02 Negative (N) Flag
Turns ON when the result of a calculation is negative (leftmost bit of binary result ON.)
03 Not used.
04 Overflow (OF) Flag
Turns ON when an overflow occurs in a signed binary calculation. Read-
only
05 Underflow (UF) Flag
Turns ON when an underflow occurs in a signed binary calculation.
06 Differential Monitor Complete Flag
Turns ON when differential monitoring is completed.
07 STEP(08) Execution Flag
Turns ON for 1 cycle only at the start of process based on STEP(08).
08 to 15 Not used.
SR 255 00 0.1-second clock pulse (0.05 second ON; 0.05 second OFF) Read-
01 0.2-second clock pulse (0.1 second ON; 0.1 second OFF) only
02 1.0-second clock pulse (0.5 second ON; 0.5 second OFF)
03 Instruction Execution Error (ER) Flag
Turns ON when an error occurs during execution of an instruction.
04 Carry (CY) Flag
Turns ON when there is a carry in the results of an instruction execution.
05 Greater Than (GR) Flag
Turns ON when the result of a comparison operation is “greater.”
06 Equals (EQ) Flag
Turns ON when the result of a comparison operation is “equal,” or when the result of an
instruction execution is 0.
07 Less Than (LE) Flag
Turns ON when the result of a comparison operation is “less.”
08 to 15 Not used.

Note DM 6601 in the PC Setup can be set to maintain the previous status of the

Forced Status Hold Bit (SR 25211) and the I/O Hold Bit (SR 25212) when power

is turned OFF. Refer to 4-5 PC Setup for details.

4-4 AR Area

These bits mainly serve as flags related to CPM2B operation. These bits retain

their status even after the CPM2B power supply has been turned off or when

operation begins or stops.

Word(s) Bit(s) Function
AR 00,
AR 01 00 to 15 Not used.
AR 02 00 to 07 Not used.
08 to 11 Number of Expansion I/O Boards Connected
12 to 15 Not used.
AR 03 to
AR 07 00 to 15 Not used.