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154
Holding Area (H)
Section 4-6
4.
When PLC operation is stopped when a fatal error other than an
FALS(007) error occurs. (The contents of the Work Area will be retained
when FALS(007) is executed.)
4-6
Holding Area (H)
The Holding Area contains 512 words with addresses ranging from H0 to
H511 (bits H0.00 to H511.15). These words can be used in programming.
Holding Area Initialization
Data in the Holding Area is not cleared when the power is cycled or the PLC’s
operating mode is changed from PROGRAM mode to RUN or MONITOR
mode or vice-versa.
A Holding Area bit will be cleared if it is programmed between IL(002) and
ILC(003) and the execution condition for IL(002) is OFF. To keep a bit ON
even when the execution condition for IL(002) is OFF, turn ON the bit with the
SET instruction just before IL(002).
Self-maintaining Bits
When a self-maintaining bit is programmed with a Holding Area bit, the self-
maintaining bit won’t be cleared even when the power is reset.
Note
1.
If a Holding Area bit is not used for the self-maintaining bit, the bit will be
turned OFF and the self-maintaining bit will be cleared when the power is
reset.
2.
If a Holding Area bit is used but not programmed as a self-maintaining bit
as in the following diagram, the bit will be turned OFF by execution condi-
tion A when the power is reset.
3.
H512 to H1535 are used as a Function Block Holding Area. These words
can be used only for function block instances (internally allocated variable
area). These words cannot be specified as instruction operands in the user
program.
Precautions
When a Holding Area bit is used in a KEEP(011) instruction, never use a nor-
mally closed condition for the reset input if the input device uses an AC power
supply. When the power supply goes OFF or is temporarily interrupted, the
input will go OFF before the PLC’s internal power supply and the Holding Area
bit will be reset.
H0.00
H0.00
A
H0.00
Input
Unit
Set input
Reset input
H1.00
Summary of Contents for CP1L CPU UNIT - 03-2009
Page 1: ...Cat No W462 E1 06 CP1L CPU Unit SYSMAC CP Series CP1L L_0D_ CP1L M_0D_ OPERATION MANUAL...
Page 2: ......
Page 4: ...iv...
Page 10: ...x...
Page 22: ...xxii...
Page 34: ...xxxiv Conformance to EC Directives 6...
Page 70: ...36 Function Blocks Section 1 5...
Page 584: ...550 Trouble Shooting Section 8 7...
Page 627: ...593 Sample Application Section 9 12 Network Settings Network Tab Network Settings Driver Tab...
Page 630: ...596 Sample Application Section 9 12...
Page 654: ...620 Troubleshooting Unit Errors Section 11 4...
Page 662: ...628 Replacing User serviceable Parts Section 12 2...
Page 668: ...634 Standard Models Appendix A...
Page 698: ...664 Auxiliary Area Allocations by Function Appendix C...
Page 746: ...712 Auxiliary Area Allocations by Address Appendix D...
Page 773: ...739 Connections to Serial Communications Option Boards Appendix F Connecting to Unit...
Page 774: ...740 Connections to Serial Communications Option Boards Appendix F...
Page 806: ...772 Index...
Page 808: ...774 Revision History...