The interface between PLC and electrical circuit is accomplished through input and output(I/O).The I/O module integrates the I/O circuit of the PLC,its input register reflects the state of the input signal,and the output point reflects the state of the output latch.The input module converts the electrical signal into a digital signal and enters the PLC system,and the output module is the opposite.I/O is divided into digital input(DI),digital output(DO),analog input(AI),analog output(AO)and other modules.
The switch quantity refers to the signal with only two states of on and off(or 1 and 0),and the analog quantity refers to the continuously changing quantity.Commonly used I/O classifications are as follows:
Switch quantity:according to the voltage level,there are 220VAC,110VAC,24VDC,according to the isolation method,there are relay isolation and transistor isolation.
Analog:divided by signal type,there are current type(4-20mA,0-20mA),voltage type(0-10V,0-5V,-10-10V),etc.,according to accuracy,there are 12bit,14bit,16bit,etc..
In addition to the above general IO,there are also special IO modules,such as thermal resistance,thermocouple,pulse and other modules.
Determine the module specification and quantity according to the number of I/O points.The number of I/O modules can be more or less,but the maximum number is limited by the basic configuration capability that the CPU can manage,that is,the maximum number of backplane or rack slots.
PLC与电气回路的接口,是通过输入输出部分(I/O)完成的。I/O模块集成了PLC的I/O电路,其输入暂存器反映输入信号状态,输出点反映输出锁存器状态。输入模块将电信号变换成数字信号进入PLC系统,输出模块相反。I/O分为开关量输入(DI),开关量输出(DO),模拟量输入(AI),模拟量输出(AO)等模块。
开关量是指只有开和关(或1和0)两种状态的信号,模拟量是指连续变化的量。常用的I/O分类如下:
开关量:按电压水平分,有220VAC、110VAC、24VDC,按隔离方式分,有继电器隔离和晶体管隔离。
模拟量:按信号类型分,有电流型(4-20mA,0-20mA)、电压型(0-10V,0-5V,-10-10V)等,按精度分,有12bit,14bit,16bit等。
除了上述通用IO外,还有特殊IO模块,如热电阻、热电偶、脉冲等模块。
按I/O点数确定模块规格及数量,I/O模块可多可少,但其最大数受CPU所能管理的基本配置的能力,即受最大的底板或机架槽数限制。
SORENSEN SRL 10-25 0-10V@0-25A METERED REGULATED VARIAB
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SORENSEN SRL 40-6 DC POWER SUPPLY 0-40VDC