113
Input Unit
A
NEVER
S
R
KEEP(11)
HR 0003
A
Bits used in KEEP are not reset in interlocks. Refer to the
5-7
INTERLOCK
and INTERLOCK CLEAR – IL(02) and ILC(03)
for details.
If a HR bit or an AR bit is used, bit status will be retained even during a
power interruption. KEEP(11) can thus be used to program bits that will main-
tain status after restarting the PC following a power interruption. An example
of this that can be used to produce a warning display following a system
shutdown for an emergency situation is shown below. Bits 00002, 00003, and
00004 would be turned ON to indicate some type of error. Bit 00005 would be
turned ON to reset the warning display. HR 0000, which is turned ON when
any one of the three bits indicates an emergency situation, is used to turn ON
the warning indicator through 00500.
HR 0000
00500
00002
00003
00004
00005
Reset input
Indicates
emergency
situation
Activates
warning
display
Address
Instruction
Operands
00000
LD
00002
00001
OR
00003
00002
OR
00004
00003
LD
00005
00004
KEEP(11)
HR
0000
00005
LD
HR
0000
00006
OUT
00500
S
R
KEEP(11)
HR 0000
KEEP(11) can also be combined with TIM to produce delays in turning bits
ON and OFF. Refer to
5-11-1
TIMER – TIM
for details.
5-8
INTERLOCK and INTERLOCK CLEAR – IL(02) and ILC(03)
Ladder Symbol
IL(02)
Ladder Symbol
ILC(03)
IL(02) is always used in conjunction with ILC(03) to create interlocks. Inter-
locks are used to enable branching in the same way as can be achieved with
TR bits, but treatment of instructions between IL(02) and ILC(03) differs from
that with TR bits when the execution condition for IL(02) is OFF. If the execu-
tion condition of IL(02) is ON, the program will be executed as written, with
an ON execution condition used to start each instruction line from the point
where IL(02) is located through the next ILC(03). Refer to
4-6-7 Branching
Instruction Lines
for basic descriptions of both methods.
If the execution condition for IL(02) is OFF, the interlocked section between
IL(02) and ILC(03) will be treated as shown in the following table:
Example
Description
INTERLOCK and INTERLOCK CLEAR – IL(02) and ILC(03)
Section 5-8