Direct Variable User Programming Memory - LS Electric XGB PLC from AutomationDirect

User controlled direct variables are defined by the processor but are used strictly by the user. These memory locations can be user data storage areas, but one of their primary uses is as a pass through for information sent via Modbus communication. The PLC uses %M and %W locations for user controlled direct variable memory. To view the user controlled direct variable memory for this PLC, we are going to look at the “Global/Direct Variables” screen. To get there we will go to the project browser on the left side of the screen and double click on “Global/Direct Variables.” A new window opens with the “Global/Direct Variables” screen and several tabs. The “Direct Variable Comment” tab will allow the user to view any direct variable. To see the %M variables we will go to the “Direct Variable” drop down and select %MW0. To see the %W variables and comments, select %WW0. The difference between %M and %W locations, is in their retain settings. %W memory locations are always retained. %M memory locations can be set to be retained or not retained. By default, %M memory locations are not retained. To change them to retained memory we go to the project browser on the left side of the screen and double click on “Basic Parameter.” A new pop-up window opens with the “Basic Parameter Setting” screen. We go to the “Retain Area Setup” tab and check the box next to “M area retain setting.” We can then select what range of %M memory addresses we wish to be retained.