XEM CPU Reset & Clear Commands - LS Electric XGB PLC from AutomationDirect

The XG5000 software has multiple levels of CPU resets. The programmer has the option to use the Reset command, the Overall reset command, the clear PLC command, and the clear all PLC command. The reset command performs a simple reboot of the CPU. As the CPU completes the rebooting cycle, it will delete error and warning information to allow the boot up. If an issue remains, the error or warning will come back. The Overall reset command performs a reboot of the PLC, clearing error and warning information as well as clearing the retained memory and any forced I/O. The Clear PLC command allows the programmer to select which sections of the PLC will be cleared. The user can clear configurations, programs, or specific memory locations from the CPU with this command. The Clear All PLC command will empty out the entire CPU of any stored information including the CPU IP address. It clears out all programs, memory, forces, configurations, communication, comments etc. This should be the very last step taken for resetting a PLC and will usually only be used when a CPU needs to be repurposed for an entirely new project from the ground up. It is important to note that none of these reset or clear commands may be undone. We need to be very careful in selecting which of these to use and when. Once they have been done, there is no going back. We can always write a program back to the CPU, but accumulated counters, timers, and other real time data cannot be recovered. In order to initiate the reset commands or the Clear PLC command we must be online with the CPU. We can initiate the Clear All PLC command offline as it will force us to then connect to our CPU to execute the Clear All. We strongly recommend only initiating the Clear All PLC command for a CPU that is already connected to the software. This will ensure we clear the correct CPU. If we were to initiate a connection as part of a Clear All PLC command, it will clear whichever PLC we connect to as soon as we select connect. If we have multiple PLCs, and are connecting via Ethernet, we might easily clear the wrong one. To perform a clear or reset, we will go online with the PLC by pressing the “Connect/Disconnect” button in the upper left of the screen. We can select our desired reset or clear command by going to “Online>Reset/Clear.” We can then select which reset or clear command we want. If we select the reset or overall reset commands, the software asks us to confirm the reset request. Once we do this it will reboot the CPU which will close our connection. We will then have to reconnect to be back online with the CPU. Both these commands may be done in stop or run mode, but the CPU mode switch must be in the “Stop” position. Once the PLC reboots it will stay in the same mode it was in when the reset was requested. If we want to select the clear PLC command, we must be online and the PLC must be in stop mode. Selecting “Clear PLC” will open the “Clear – LSPLC” pop up window. In this window on the “Item” tab is a list of configurations, parameters, programs, or network links that we can select or unselect to be part of the reset. There is also a memory tab which shows the internal memory locations. We can select any of these ranges, and even customize which addresses in the range should be cleared. Finally, if we select the “Clear All PLC” command this may be done online or offline and will delete everything in the PLC including the IP address. This must be done with the mode switch in the stop position, but the CPU may be in stop or run mode as the software will force us to put the CPU in stop mode to perform the Clear All. It is very important to note that once we have performed this Clear All, the only supported way to connect to the PLC again is using the USB cable initially. The Ethernet connection will not work until after we have rewritten a valid IP address to the CPU using the USB connection. Also, it will not be possible to read a project from the CPU since no project is present. We will need to either create a new project or open an existing project and write it to the CPU to move forward. To recap, all 4 resets require the mode switch to be in the stop position. The reset, overall reset, and clear PLC commands require the software to be connected to the CPU, and the Clear All PLC command should only be used when connected to avoid erasing the wrong CPU. The reset and overall reset commands may be executed in run or stop mode, whereas the ClearPLC command requires stop mode, and the Clear All PLC command will force the CPU into stop mode. Whether we need a simple reboot, custom clearing option, or a complete reset of the PLC the XG5000 software has an option that will work for us.