33
Carry Flag, CY
Bit 0312 turns ON when a carry occurs as a result
of arithmetic operation.
Less Than Flag, LE
Bit 0313 turns ON when the result of a comparison
operation between two operands shows the first to
be less than the second.
Equals Flag, EQ
Bit 0314 turns ON when the result of a comparison
shows two operands to be equal or when the result
of an arithmetic operation is zero.
Greater Than Flag, GR
Bit 0315 turns ON when the result of a comparison
operation between two operands shows the first to
be greater than the second.
For relations between arithmetic flags and instructions, refer to Appendix E.
Always ON/OFF Flags
Bit 0408 is always ON and bit 0409 is always OFF. These bits can be pro-
grammed to control external indicating devices such as an LED to monitor
the PC’s operating status. They can also be used in programming when an
instruction is to be executed every scan.
First Scan Flag
Bit 0410 turns ON when program execution starts and turns OFF after one
scan.
Step Flag
Bit 0411 turns ON for one scan when step execution is started by the STEP
instruction.
Descriptions: SP16 and SP20 Only
DR Data Transfer Enable Bit Turn bit 0515 ON to transfer DR data from EEPROM to RAM when power is
applied to the PC. This bit will be ON after the “DR Area Transfer” operation
has been performed. The status of bit 0515 is retained in a power interrup-
tion, i.e., DR data will be transferred from EEPROM to RAM when the power
is turned ON if bit 0515 is ON when power is interrupted. If you want to retain
the DR data as it was just before a power interruption, turn bit 0515 OFF with
the “Force Set/Reset” operation. Bit 0515 is turned OFF in the “Data Clear”
operation.
Maximum Scan Time Area
Bits 0700 to 0707 contain the maximum scan time since start-up in 2-digit
BCD (0.0 to 9.9 ms). The maximum scan time is reset when the PC begins
operation.
Current Scan Time Area
Bits 0708 to 0715 contain the current scan time in 2-digit BCD (0.0 to
9.9 ms).
Note The present and maximum scan time can be read out from the Programming
Console with the SP16 or SP20. Refer to 3-8-2 Reading the Scan Time for
details.
ATM1 Set Value Area
Word 08 contains the set value in BCD for analog timer 1 as set with the ad-
justment screw on the front of the CPU (SP16 and SP20 only).
ATM12Set Value Area
Word 09 contains the set value in BCD for analog timer 2 as set with the ad-
justment screw on the front of the CPU (SP16 and SP20 only).
3-2-5
LR Area
The LR area is used to pass data back and forth between PCs linked through
a Link Adapter. To use the LR area, part of the DR area must be allocated as
Memory Areas
Section 3-2