156
FX
3U
/FX
3UC
Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
7 Basic Instruction
7.1 LD, LDI
2. LDI instruction (initial logical operation, NC contact type)
3. Indexing
Devices used in LD and LDI instructions allow indexing with index registers (V and Z).
(State relays (S), special auxiliary relays (M), 32-bit counters (C), and "D
.b" cannot be indexed.)
V0 to V7 and Z0 to Z7 are available in
indexing.
When used devices are inputs (X) and
outputs (Y), values of index registers (V and
Z) are converted into octal numbers, and then
added.
Example:When the value of V0 is 10, LD
contact is set to ON (becomes
conductive) or OFF (becomes non-
conductive) by X012.
4. Bit specification of data register (D)
A bit in data register (D) can be specified as a device used in LD and LDI instructions.
When specifying a bit in data register, input "."
after a data register (D) number, and then
input a bit number (0 to F) consecutively.
Only 16-bit data registers are available.
Specify a bit number as "0, 1, 2, ... 9, A, B, ...
F" from the least significant bit.
Example:In the example shown on the left, LD
contact is set to ON (becomes
conductive) or OFF (becomes non-
conductive) by the bit 3 of D0.
Errors
• When an I/O number used in LD or LDI instruction does not exist due to indexing, M8316 (Non-existing I/O
specification error) turns ON.
• When the device number of a device (M, T or C) other than I/O used in LD or LDI instruction does not exist
due to indexing, an operation error (error code: 6706) occurs.
X000
Y000
LDIinstruction
Circuit program
List program
LDI
OUT
0000
0001
X000
Y000
Connection to bus line
ON
ON
ON
ON
X000
Y000
Timing chart
Bus line
X000V0
Y000
Circuit program
List program
LD
OUT
0000
0001
X000V0
Y000
D0.3
Y000
Circuit program
List program
LD
OUT
0000
0001
D0.3
Y000