WATCHDOG - Force Watchdog Error

Topic: DMD0155

Help File Version: 2.9.4.37

WATCHDOG - Force Watchdog Error

The Force Watchdog Error (WATCHDOG) instruction is used to generate a software or hardware watchdog error condition so that the programmer can verify that emergency shutdown conditions are being properly handled by the project that is currently running in the Do-more controller.

The Software Watchdog Timeout specifies the maximum amount of time (in milliseconds) to allow for a single scan in the controller. If this value is exceed, the controller will immediately transition to STOP mode. Follow this link for more information on setting the Software Watchdog Timeout value.

All of the Do-more controllers contain a Hardware Watchdog Timer that is used to put the controller into a safe mode if the operating system ever stops running for more than 2 seconds. Follow this link for details on Configuring the Hardware Watchdog Timer.

Note: if the input logic to this instruction is retentive, and the Mode Switch is in either the RUN or TERM position, the controller will execute the Force Watchdog Error instruction continuously. Place the Mode switch in the STOP position to break out of this condition.

Parameters:

Fire Software Watchdog - immediately generate a software watchdog error condition.

Note: this instruction will NOT generate a software watchdog timeout if the system variable $DisableSwWdog (ST37) is ON.

Fire Hardware Watchdog - immediately generate a hardware watchdog error condition.

Note: this instruction will NOT generate a hardware watchdog timeout if the system variable $DisableHwWdog (ST25) is ON.

Status Display:

The green triangle in the upper left corner indicates this is a Skipping instruction.