| 摘要 |
PURPOSE: An input circuit of a high speed counter module for a PLC(Programmable Logic Controller) is provided to improve an interruption process speed by checking a kind of pulses which are inputted or by omitting the confirmation of an addition and a subtraction. CONSTITUTION: A first multivibrator(20) detects the rising and falling edges of a first contact input and generates a pulse. A second multivibrator(30) detects the rising and falling edges of a second contact input and generates the pulse. A first buffer(60) outputs an output of the first multivibrator into a three-condition. A second buffer(70) outputs an output of the second multivibrator into the three-condition. A first multiplexer(40) outputs either an exclusive or signal or an inverted signal of the first contact input and the second contact input. A second multiplexer(50) outputs either an output of the first multiplexer or the second contact input. A first switch(10) outputs an output of the first buffer and the second buffer into a first phase input or a second phase input. [Reference numerals] (10) Bus exchange switch 1; (20) Multivibrator 1; (30) Multivibrator 2; (60) 3-state buffer 1; (70) 3-state buffer 2; (80) Bus exchange switch 2; (AA) Low when 1-phase and 1-multiplying; (BB) A contact point input; (CC,EE) B contact point input; (DD) High when 2-phase and 1-multiplying; (FF) Low when 1-phase is inputted; (GG) A phase input; (HH) B phase input |
