Mitsubishi PLC warning clock command - Solutions - Huaqiang Electronic Network

SMD Aluminum Electrolytic Capacitor

5032 OSC Clock Vibration

Photocoupler

(1) The mnemonic, instruction code, operand, and program steps of the watchdog command are listed in Table 6-6.

(2) The application principle of the instruction is illustrated in Figure 6-9.

(3) Instruction description:
The WDT instruction is used to reset the watchdog timer within the control program. If the scan cycle time of the executing program exceeds 200 ms (between 0 steps and END or FEND instructions), the PLC will stop running. To prevent this, the WDT instruction should be inserted at appropriate points in the program to refresh the watchdog timer, allowing the program to continue execution until the END instruction is reached. For example, if a program has a scan time of 240 ms, it can be split into two 120 ms segments, with a WDT instruction placed between them, as shown in Figure 6-10.

Additionally, if you need each scan cycle to exceed 200 ms, you can use the MOV instruction to write the desired value into the special data register D8000, as demonstrated in Figure 6-10. This allows for more flexible configuration of the watchdog timer based on specific application requirements.