Mitsubishi Electric MELSEC iQ-F Series - Page 85

8 SFC PROGRAM
8.2 Structure
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8
Assigning the step relay (S) areas to steps
The step relay is a device corresponding to each step in the SFC program. It is on when the relevant step is active (even in
the stop or hold state) and is off when the relevant step is inactive.
Step relays are assigned as follows.
• Step relays are assigned sequentially in order of block No. starting from block 0 in an SFC program and in order of step No.
within a block.
• No step relay is assigned to any non-existing block No.
• Step relays are assigned to missing step Nos. in one block. The bits of the missing numbers are constantly off.
• All bits after the step relays assigned in the last block are off.
Ex.
The following example shows the step relay assignments of the following block configuration.
Any step No. can be assigned to each step (except end step).
• Assign step Nos. in ascending order wherever possible because any missing step No. will decrease the
maximum number of steps that can be created.
• The step No. other than step No. 0 (S0) cannot be used for the initial step of the top line and left end.
Step No. 0 is assigned to the initial step in a block.
For the step Nos. that can be used per block, refer to the following.
Page 73 Specifications
Any step No. exceeding the upper limit cannot be assigned. Any step No. must be unique within a block. Same step Nos. can
be used in different blocks.
To specify a step relay in another block, use the following format.
Ex.
Specifying step No. 23 in block No. 12
• Block0: The largest step No. is 8, and step No. 3 and 6 are missing.
• Block1: Missing
• Block2: The largest step No. is 12, and step No. 3 is missing.
• Block3 and after: Missing
(1) Stored data
(2) Step Nos. in a block
(3) All 0s for missing blocks
Program type Device notation Description
SFC program In the same block S23 The block name can be omitted when specifying a step in the
same block.
Other than block 12 BL12\S23 Specify the target block No. and step No.
Sequence program other
than SFC program
Specifying the current target block S23 The block name can be omitted when specifying a step in the
target block.
Specifying a block different from the current
target block
BL12\S23 Specify the target block No. and step No.
b15
S6
b14
S5
b13
S4
b12
-
0
b11
S2
b10
S1
b9
S0
b8
S8
b7
S7
b6
-
0
b5
S5
b4
S4
b3
-
0
b2
S2
b1
S1
b0
S0
b15 b14
0
b13
0
b12
0
b11
0
b10
0
b9
0
b8
0
b7
0
b6
0
b5
S12
b4
S11
b3
S10
b2
S9
b1
S8
b0
S7
Block2 Block0
(1)
(2)
(1)
(2)
(3) Block2
0
S15 to S0
S31 to S16