Mitsubishi Electric MELSEC FX3U Programming Manual page 692

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
Explanation of function and operation
FNC224 to FNC230 are data comparison instructions connected to bus lines.
The contents of
conductive (ON) or non-conductive (OFF) depending on the comparison result.
FNC No.
224
225
226
228
229
230
Cautions
1. Negative value
When the most significant bit is "1" in the data stored in
comparison.
• In the 16-bit operation: bit 15
• In the 32-bit operation: bit 31
2. When using 32-bit counters (including 32-bit high speed counters)
Make sure to execute the 32-bit operation (such as "LDD=", "LDD>" and "LDD<") when comparing 32-bit
counters (C200 to C255).
If a 32-bit counter is specified in the 16-bit operation (such as "LD=", "LD>" and "LD<"), a program error or
operation error will occur.
3. Programming of data comparison instructions
When programming in GX Developer, symbols "≤" and "≥" cannot be input.
Separate "≤" into "<" and "=", and separate "≥" into ">" and "=" in input.
The input procedure is described below:
Operating procedure
a) Display the circuit program edit window, and put the cursor in a position where a data comparison
instruction is to be used.
b) Input "Instruction" → "space" → "value or device" → "space" → "value or device".
For an input example, refer to "Instruction input window in GX Developer" shown below.
c) Click the [OK] button.
d) Input other contacts and coil drive units consecutively.
Instruction input window in GX Developer
690
are compared with the contents of
S
1
16-bit instruction
LD=
LD>
LD<
LD<>
LD<=
LD>=
<Input example for 16-bit operation>
<Input example for 32-bit operation>
28.1 FNC224~230 – LD =, >, <, <>, <=, >= / Data Comparison
in the binary format, and a contact becomes
S
2
32-bit instruction
LDD=
LDD>
LDD<
LDD<>
LDD<=
LDD>=
or
S
1
28 Data Comparison – FNC220 to FNC249
ON condition
S = S
1 2
>
S S
1 2
<
S S
1 2
≠
S S
1 2
<=
S S
1 2
>=
S S
1 2
, it is regarded as a negative value in
S
2
OFF condition
≠
S S
1 2
<=
S S
1 2
>=
S S
1 2
=
S S
1 2
>
S S
1 2
<
S S
1 2