There is an n on the left side of qf2 in plc, and |N| is a falling edge trigger instruction, which detects the falling edge of the signal and generates a pulse with a scanning period width.

In addition, |P| is a rising edge trigger command, which detects the rising edge of the signal and generates a pulse with a scanning period width.

Two instructions are used to detect the change of state (the signal appears or disappears).

Common PLC splitters are made of silicon dioxide (SiO2). In fact, PLC technology involves a wide range of materials, such as glass/silica (Shi Ying/silica /SiO2), lithium niobate (LiNbO3) and III-V semiconductor compounds (such as InP and GaAs). ), and silicon on insulator, SOI/SIMOX/SIMOX).