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 less than S2.
LDD Execution Condition
When the result of the instruction execution of the expression D0 < D2 (986,542 < -23,461) is FALSE, the coil, Y1.3, is deenergized.
When the result of the instruction execution of the expression D0 < D2 (-325,654 < -23,461) is TRUE, the coil, Y1.3, is energized.
Memory Monitor
ANDD Execution Condition
When the result of the instruction execution of the expression D5 < D7 (83,648 < 25,652) is FALSE, and the contact, M0.0 is ON (1), the coil, Y1.4, is deenergized.
When the result of the instruction execution of the expression D5 < D7 (-83,648 < 25,652) is TRUE, and the contact, M0.0 is ON (1), the coil, Y1.4, is energized.
Memory Monitor
ORD Execution Condition
When the result of the instruction execution of the expression D10 < D12 (2,356,655 < -265,578) is FALSE, or the contact, M0.1 is ON (1), the coil, Y1.5, is energized.
When the result of the instruction execution of the expression D10 < D12 (8,954 < 851,582) is TRUE, and the contact, M0.1 is OFF (0), the coil, Y1.5, is energized.
Memory Monitor
