Control block is an important part of DOP series of HMI. It can be controlled via PLC to carry out the following operations: screen switch, buzzer on and off, backlight on and off, security level settings, curve drawing, and recipe transmission, etc. Please ensure that the settings of control block are set correctly, otherwise it may cause that many functions could not be executed or lead to many error operations. The user can refer to the chapter 5 “Control Block and Status Block” of HMI user manual for more descriptions. In fact, when editing PLC programs, it is recommended not to use the address of the control block.