Sfrd (Fnc 39) - Mitsubishi FX1S Series Programming Manual

FX Series Programmable Controlers
5.4.10

SFRD (FNC 39)

Mnemonic
SFRD
FNC 39
(Shift
register read)
16 BIT OPERATION
Points to note:
a) FIFO is an abbreviation for 'First-In/ First-OUT'.
b) Only n pieces of data may be read from a FIFO stack. This is because the stack requires
-1
that the first register, the head address (S) is used to contain information about the current
length of the FIFO stack.
c) This instruction will always read the source data from the register S
d) This instruction should be used in conjunction with SFWR FNC 38. The n parameter in both
instructions should be equal.
Function
This instruction KnY, KnM,
reads and KnS,
reduces FIFO T, C, D,
stack- must be KnY,
used with SFWR KnM,KnS,
FNC 38 T, C, D
32 BIT OPERATION
Operands
S D
KnY, KnM,
KnS,
T, C, D,
KnY,
KnM,KnS,
T, C, D, V, Z
PULSE-P
Operation:
The source device (S) identifies the head address
of the FIFO stack. Its contents reflect the last entry
point of data on to the FIFO stack, i.e. where the
end of the FIFO is (current position).
This instruction reads the first piece of data from
the FIFO stack (register S
within the stack 'up' one position to fill the read
area and decrements the contents of the FIFO
head address (S) by 1. The read data is written to
the destination device (D).
When the contents of the source device (S) are
equal to '0' (zero), i.e. the FIFO stack is empty, the
flag M8020 is turned ON.
Applied Instructions 5
FX FX FX
1N
1S
Program steps
n
K,H, SFRD,
SFRDP:
7 steps
Note:
2≤ n≤ 512
Flags
), moves all of the data
+1
.
+1
5-52
FX
2N 2NC
Zero M8020