7. APPLICATION INSTRUCTIONS
7
−
83
MELSEC-A
DFRO
Reads the (n3
×
2) words of data from the buffer memory address specified by n2 in
the special module/special block specified by n1 and writes the data to the
A1FXCPU beginning with the device number specified by (D).
A1FXCPU
n2
Device number
specified by (D)
Buffer memory in
the special module/
special block
(n3 2)
words
(n3 2) points
n2+1
Execution
FROM and DFRO instructions are executed every scan while the read instruction is
Conditions ON.
FROMP and DFROP instructions are executed only once at the rising edge (OFF
→
ON) of the read instruction.
Operation Errors
In the following cases, operation error occurs and the error flag turns on.
•
Access to a special module/special block is not possible.
•
n1 designation is other than 0 to 7
•
When "n3" points which start with the device specified at (D) exceed the specified
device
range.
REMARK
Set the order number of the special module/special block in question to "n1", counted from the
A1FXCPU.
OFF
ON
Executed
per scan
Executed
per scan
Executed
only once
Executed
only once
P
Read command
A1FXCPU
Expansion unit/
Expansion block
Special module/
Special block
Special module/
Special block
Set 0 at n1
Set 1 at n1
Содержание MELSEC-A series
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