With the Maple Systems cMT Series, LW/LB are local registers whereas PLW/PLB are client registers.
PLW and PLB memory is local memory to each client that is being served by a cMT device and is inaccessible from anywhere other than locally on that client device. If you remote access to a cMT device through cMT Viewer or EasyAccess 2.0, you are essentially duplicating and running the entire project that is hosted on the server. This means that the device you are using will reserve its own PLB/PLW memory that is local to itself.
One way to demonstrate this concept is to create a project in EBPro in which there is a toggle switch and a bit lamp assigned to a PLB bit. Run the project on a cMT device with a display and remote into the server as well. Toggle the switch on the local client; you will see the lamp turn ‘on’ on the display, but not on the remote client’s display. Toggle the switch on the remote display, and you will see the lamp turn ‘on’ on the remote display but not on the local display.
For extra measure, add another toggle and bit lamp assigned to an LB bit. Toggle this switch and the lamp will turn ‘on’ on both displays. This is because PLB/PLW memory is separate to each device and LB/LW memory is shared.