Comparison Uses
There are three types of comparison uses:
- LDD (Ladder Diagram)
- ANDD
- ORD
The following compare instructions can be used as a:
- DWORD standalone execution condition (LDD)
- DWORD and execution condition (ANDD)
- DWORD or execution condition (ORD)
Instruction Parameters
Supported PLC Series
| PLC-AES | PLC-FB | PLC-ES |
|---|---|---|
| ✓ | ✓ | ✓ |
Supported Data Registers
| M | X | Y | K | L | F | T | C | S | Z | R | Q | D | @D | Constant | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| S1 | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | – | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
| S2 | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | – | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ |
Supported Flags
| Flag | Bit | Support |
|---|---|---|
| Error | F11.0 | ✓ |
| Zero | F11.1 | – |
| Carry | F11.2 | – |
Number of Steps
| Steps |
|---|
| 3 |
Operands
| Operand | Description |
|---|---|
| S1 | The first operand. Entries are signed DWORD data registers or constants. The signed value range is -2,147,483,648 ~ 2,147,483,647 (232). The Hexadecimal value range is H00000000 ~ HFFFFFFFF. Only DWORD values will be compared. Only signed or Hexadecimal values will be compared. |
| S2 | The second operand. Entries are signed DWORD data registers or constants. The signed value range is -2,147,483,648 ~ 2,147,483,647 (232). The Hexadecimal value range is H00000000 ~ HFFFFFFFF. Only DWORD values will be compared. Only signed or Hexadecimal values will be compared. |
Notice
Error Flag (F11.0) Notice
The error flag, F11.0, will be ON for one scan when the address of the data register assigned by @D exceeds the range of the data register, D. The range of the data register, D, is dependent on the CPU type.
Signed Overflow
DWORD data register entry behaves as follows:
- If the value of S1 or S2 exceeds the smallest signed value -2,147,483,648, the value will be set to -2,147,483,648 with no warning.
- If the value of S1 or S2 exceeds the largest signed value 2,147,483,647, the value will be set to 2,147,483,647 with no warning.
Ladder Diagram Examples
D>=
The D>= instruction compares a DWORD value, S1, to another DWORD value, S2, and executes if S1 is greater than or equal to S2.
LDD Execution Condition
When the result of the instruction execution of the expression D14 ≥ D16 (-457,913 ≥ 987,421) is FALSE, the coil, Y4.3, is deenergized.
When the result of the instruction execution of the expression D14 ≥ D16 (13,556 ≥ 0) is TRUE, the coil, Y4.3, is energized.
Memory Monitor
ANDD Execution Condition
When the result of the instruction execution of the expression D18 ≥ D20 (-5,656,565 ≥ 1,211,212) is FALSE, and the contact, M0.0 is ON (1), the coil, Y4.4, is deenergized.
When the result of the instruction execution of the expression D18 ≥ D20 (5,656,565 ≥ 1,211,212) is TRUE, and the contact, M0.0 is ON (1), the coil, Y4.4, is energized.
Memory Monitor
ORD Execution Condition
When the result of the instruction execution of the expression D22 ≥ D24 (-98,765,432 ≥ -87,654,321) is FALSE, or the contact, M0.1 is ON (1), the coil, Y4.5, is energized.
When the result of the instruction execution of the expression D22 ≥ D24 (-87,654,321 ≥ -87,654,321) is TRUE, and the contact, M0.1 is OFF (0), the coil, Y4.5, is energized.
Memory Monitor
