810-800256-015 REV.C 半导体基板

Description

810-800256-015 REV.C 半导体基板

输入电路连接输入电路是PLC接收信号(-般为0-40MA直 流电流或0-10V直流电压信号，用于模拟)的端口，输入连接是指外部输入器件(任何无源触点和集电极打开的NPN三极管)通过输入电路闭合,同时输入指示发光二_极管。常用的外部输入设备包括按钮、接近开关、转换开关、dip开关、 各种电感器等，它们是向系统发出各种控制信号的主要命令电器。

(1) PLC输入模块与主电气设备的连接
图中松下PLC为直流点输入，即这样输入点共用一-个共同端子COM, COM端带DC24V电源，编写程序时要注意使用的外部设备是常闭触点还是常开触点。

输入端电气原理图中的停止按钮SB0使用串在控制线上的常闭触点进行关断控制。启动按钮SB1,触点常开。设计中的两个梯形图实现了相同的控制功能，但停止信号X0使用不同的触点类型，因此连接端点的外部停止按钮触点类型不同。

/O分配s0-x0、s_ 1-x1,输出K0-Y0。 当外部使用长闭合触点时，不操作按钮，输出Y0正常连接,在PLC控制系统中，外部开关无论启动或停止一般选择常开型。

(2)接近开关与PLC输入模块之间的连接在PLC控制系统设计中的布线工作比例很小，但它是编程设计的基础。为了保证接线工作正确，需要对PLC的输入输出电路有一个清晰的认识。

1. PLC直流输入电路:有源型(共阳极)输入电路，漏电型(共阴极)输入电路。所以PLC漏电输入电路的COM端是外部直流电源的正极,如西门子S7-400PLC直流输入模块的COM端必须接在外部直流电源的正极上。所以西门子PLC输入的信号为低压信号,如果外部信号为高压信号则应通过中间继电器进行转换。

2.PLC交流输入电路电压一般为AC120V或AC230V, 经过电阻限流和电容隔离后整流成直流三个环节，因此输入信号延迟时间比直流电路长,但输入端电压高，输入信号可靠性高，- 般用于环境恶劣，响应性不高的场合。

(3)开关信号与PLC输入模块的连接对于不同的PLC输入电路应正确选择传感器(NPN或PNP)的输入方式，NPN型传感器动作时，OUT端为0V，(NPN型输出端OUT应接漏电型PLC输入端)输出低电平信号。PNP传感器动作, OUT端为+V,输出高电平信号。

810-800256-015

810-800256-015 REV.C 半导体基板

Input circuit connection The input circuit is the port of the PLC to receive the signal (generally 0-40MA direct current or 0-10V DC voltage signal, for analog), the input connection refers to the external input device (any passive contact and collector open NPN triode) closed through the input circuit, while the input indicating light emitting diode. Commonly used external input devices include buttons, proximity switches, transfer switches, dip switches, various inductors, etc., which are the main command appliances that send various control signals to the system.

(1) Connection between PLC input module and main electrical equipment
The Panasonic PLC in the figure is a DC point input, that is, the input point shares a common terminal COM, COM end with DC24V power supply, when writing the program, pay attention to the use of external equipment is normally closed contact or normally open contact.

The stop button SB0 in the input electrical schematic uses normally closed contacts strung along the control line for shutdown control. Start button SB1, contact normally open. The two trapezoids in the design implement the same control function, but the stop signal X0 uses different contact types, so the external stop button contact types connecting the endpoints are different.

/O allocates s0-x0, s_ 1-x1, and outputs K0-Y0. When the external use of long closed contact, do not operate the button, the output Y0 normal connection, in the PLC control system, the external switch whether start or stop generally choose normally open type.

(2) The connection between the proximity switch and the PLC input module has a small wiring work proportion in the design of the PLC control system, but it is the basis of programming design. In order to ensure that the wiring works correctly, it is necessary to have a clear understanding of the input and output circuits of the PLC.

1.PLC DC input circuit: active type (common anode) input circuit, leakage type (common cathode) input circuit. Therefore, the COM end of the PLC leakage input circuit is the positive terminal of the external DC power supply, such as the COM end of the Siemens S7-400PLC DC input module must be connected to the positive terminal of the external DC power supply. Therefore, the input signal of Siemens PLC is a low-voltage signal, and if the external signal is a high-voltage signal, it should be converted by an intermediate relay.

2.PLC AC input circuit voltage is generally AC120V or AC230V, rectified into DC three links after resistance current limiting and capacitor isolation, so the input signal delay time is longer than the direct current circuit, but the input terminal voltage is high, the input signal reliability is high, generally used in bad environment, responsiveness is not high occasions.

(3) The connection between the switch signal and the PLC input module for different PLC input circuits should correctly select the input mode of the sensor (NPN or PNP), when the NPN type sensor is operated, the OUT end is 0V, (NPN type output OUT should be connected to the leakage type PLC input end) output low level signal. PNP sensor action, OUT end is +V, output high level signal.