In the industrial control host or industrial control computer, the term "watchdog" often appears? What does watchdog mean?
The detailed diagram of the internal structure of our industrial computer (watchdog is a program, and all the chips embedded in our motherboard support watchdog writing).
Let’s take a look at the definition of Baidu Encyclopedia: "In a microcomputer system composed of a single-chip microcomputer, the work of the single-chip microcomputer is often interfered by the external electromagnetic field, which causes data confusion in various registers and memory, and causes program pointer errors. If you are not in the program area, if you take out the wrong program instructions, you will fall into an infinite loop, the normal operation of the program will be interrupted, and the system controlled by the single-chip microcomputer will not continue to work normally, which will cause the entire system to stall and cause unpredictable consequences.
The watchdog timer is a piece of hardware, usually built into a single-board computer (SBC) or embedded PC. It can cause a reset when it determines that the system has been suspended or is no longer executing the correct code sequence.
A well-designed watchdog mechanism should at least capture events that suspend the system. In an electrically noisy environment, a power failure may destroy the program counter, stack pointer, or data in RAM. Even if the code is completely error-free, the software may crash. This is the kind of short-lived failure that regulators will capture.
Errors in the software can cause the system to hang, so it is better to fix the root cause rather than relying on the watchdog timer. In complex embedded systems, there may be no guarantee that there are no errors, but by using a monitoring program, you can prevent these errors from hanging the system indefinitely.
From the simple text definition, most watchdogs are a timer composed of hardware, and there are also software-controlled timers as watchdogs. The function of the watchdog is that when the program runs away, the program cannot clear the watchdog to 0, so the watchdog will overflow soon after the program runs away and generate a reset signal to the MCU to make the program return to the starting point.
Let me explain it to you from a vivid analogy: "The watchdog is to prevent the CPU from entering an endless loop or crashing. Just like a watchdog, it will not bark if you feed it regularly, otherwise... it will keep going. 'Wow! Wow! Wow!'Crowd unceasingly".
The industrial machine watchdog is used as a timer to monitor the status of PLC scan time. Watchdog technology is often applied in electronic technology, not only PLC, but also single-chip computers. The role of the watchdog cannot be ignored. As we all know, the PLC program working mechanism adopts a cyclic scanning working mechanism, and each cycle must have a time, which is the scanning time. The scanning time must be limited, and this limit cannot be exceeded. Once the limit is exceeded, it means that there is a problem with the PLC scanning mechanism. The problem is generally that the user has "legitimate and unreasonable" when programming. In this case, it must stop and alarm. What is used for monitoring? Scan time monitor, a system timer, commonly known as "watchdog". Once the watchdog is activated, the result is a PLC shutdown alarm.
Anrecson industrial computer or industrial tablet computer, if the customer needs to increase the watchdog function, we will provide the watchdog program to the customer.
