IC698PSA350D GE通用电器 电源模块 控制器 PLC卡件

IC698PSA350D GE通用电器 电源模块 控制器 PLC卡件

作为一种工业控制电子装置，PLC若不能对这些量进行控制，那是一大不足，为此各PLC厂家都在这方面进行大量的开发。目前，不仅大型、中型机可以进行模拟量控制，就是小型机，也能进行这样的控制。PLC进行模拟量控制，要配置有模拟量与数字量相互转换的A／D、D／A单元。它也是I/O单元，不过是特殊的I/O单元。

A/D单元是把外电路的模拟量，转换成数字量，然后送入PLC；D/A单元，是把PLC的数字量转换成模拟量，再送给外电路。作为一种特殊的I/O单元，它仍具有I/O电路抗干扰、内外电路隔离、与输入输出继电器（或内部继电器，它也是PLC工作内存的一个区，可读写）交换信息等等特点。

 这里的A/D中的A，多为电流，或电压，也有温度。D/A中的A，多为电压，或电流。电压、电流变化范围多为0～5V，0～10V，4～20mA，有的还可处理正负值的。

As an industrial control electronic device, if PLC can not control these quantities, it is a major deficiency, so the PLC manufacturers are in this area to carry out a lot of development. At present, not only large and medium-sized machines can carry out analog control, but also minicomputers can carry out such control. PLC for analog control, to be configured with analog and digital conversion of A/D, D/A units. It's also an I/O unit, but a special I/O unit.

A/D unit is to convert the analog quantity of the external circuit into a digital quantity, and then send it to the PLC; The D/A unit converts the digital quantity of the PLC into an analog quantity and then sends it to the external circuit. As a special I/O unit, it still has the characteristics of anti-interference I/O circuit, internal and external circuit isolation, and input and output relay (or internal relay, it is also a region of the PLC working memory, can read and write) exchange information and so on.

The A in A/D here is mostly current, or voltage, but also temperature. A in D/A is mostly voltage or current. The range of voltage and current is mostly 0 ~ 5V, 0 ~ 10V, 4 ~ 20mA, and some can also deal with positive and negative values.