532
Memory Areas
Appendix C
Note
Writing is not possible for the following words: SR 248 through SR 251, and SR 253 through SR 255.
Explanation of SR Bits
SR 25211 (Forced Status Hold Bit)
When the forced set/reset status is cleared, the bits that were forced will be turned ON or OFF as follows:
Forced set cleared:
Bit turned ON
Forced reset cleared:
Bit turned OFF
All force-set or force-reset bits will be cleared when the PC is switched to RUN mode unless DM 6601 in the
PC Setup has been set to maintain the previous status of the Forced Status Hold Bit when power is turned on.
This setting can be used to prevent forced status from being cleared even when power is turned on.
Turn this bit ON and OFF from a Programming Device.
SR 254
00
1-minute Clock Pulse
(30 seconds ON; 30 seconds OFF)
---
01
0.02-second Clock Pulse
(0.01 second ON; 0.01 second OFF)
---
02 to 03
Not used.
04
Overflow (OF) Flag
Turns ON when the result of a calculation is above the upper limit of signed binary data.
328
05
Underflow (UF) Flag
Turns ON when the result of a calculation is below the lower limit of signed binary data.
328
06
Differential Monitor Complete Flag
Turns ON when differential monitoring is complete.
147
07
STEP(08) Execution Flag
Turns ON for 1 cycle only at the start of process based on STEP(08).
231
08
HKY(––) Execution Flag
Turns ON during execution of HKY(––).
431
09
7SEG(88) Execution Flag
Turns ON during execution of 7SEG(88).
424
10
DSW(87) Execution Flag
Turns ON during execution of DSW(87).
427
11 to 12
Not used.
13
Communications Unit Error Flag
Turns ON when an error occurs in a Communications Unit. This flag mirrors the opera-
tion of the Communications Unit Error Flag (AR 0011).
427
14
Not used.
15
Inner Board Error Flag
Turns ON when an error occurs in an Inner Board mounted in slot 1 or slot 2. The error
code for slot 1 is stored in AR 0400 to AR 0407 and the error code for slot 2 is stored in
AR 0408 to AR 0415.
---
SR 255
00
0.1-second Clock Pulse
(0.05 second ON; 0.05 second OFF)
---
01
0.2-second Clock Pulse
(0.1 second ON; 0.1 second OFF)
---
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.”
---
Word
Bit(s)
Function
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