主营产品，备件供应，充足库存
Foxboro（福克斯波罗）：I/A Series系统，FBM全系列（现场输入/输出模块）
顺序控制、梯形逻辑控制、事故追忆处理、数模转换、输入/输出信号处理、
数据通信及处理等。
Westinghouse（西屋）：1C31系列DCS系统、CPU、OVATION系统、WDPF系统、
WEStation系统备件。
Triconex（英维思）:冗余容错控制系统、基于三重模件冗余（TMR）结构的现代化的容错控制器。
EMERSON（艾默生）:模块、卡件、驱动器等各类备件。
Here a / D, mostly current, or voltage, also has temperature. A in d/a, mostly voltage, or current. The change scale of voltage and current is mostly 0-5V, 0-10V, 4-20mA, and some can also deal with positive and negative values. The D and minicomputers here are mostly 8-bit binary numbers, and the medium and large ones are 12 bit binary numbers. A/d and d/a have single way and multi-channel. There are many input and output relays with multiple channels. With a/d and d/a units, the remaining processing is digital, which is not difficult for PLC with information processing ability. Medium and large PLC can be processed more strongly. It can not only add, subtract, multiply and divide numbers, but also open square and interpolation, but also carry out floating-point operation. Some PID instructions can perform share, differential and integral operations on error system, and then produce corresponding output. It can be calculated by the computer.
So it is possible to use PLC to control analog quantity.
PLC can control analog quantity, and a / D / a unit, and can control with PID or fuzzy control algorithm, which can get high quality control. The advantage of using PLC to control analog quantity is that the switch can also be controlled when the analog quantity is controlled. This advantage is not available by other controllers, or the completion of control is not as convenient as PLC. Of course, if the system is purely analog, PLC may not be better than regulator in performance price ratio.
3. For motion control
The actual physical quantity, besides the switch quantity, the analog quantity, also has the motion control. If the displacement of machine parts is often indicated by digital quantity. The useful way to control motion is NC, which is digital control skills. This is the control skills of accounting machines born in the United States in the 1950s. It is very popular and perfect today. Nowadays, the ratio of numerical control of metal cutting machine tools in advanced countries has exceeded 40% - 80%, some even higher. PLC is also based on the skills of the accounting machine, and is increasingly perfect. PLC can accept counting pulse, frequency can be as high as several K to dozens of kHz, can be accepted by a variety of methods, but also can be multi-channel. Some PLC also have pulse output function, pulse frequency can also reach dozens of K. with these two functions, plus PLC has data processing and operation ability, if equipped with corresponding sensors (such as rotary encoder) or pulse servo equipment, it can complete various control systems according to the principle of NC. PLC with high and medium gear also develops NC unit or motion unit, which can complete point control. The motion unit can also complete the interpolation of the curve, and control the curve motion. Therefore, if PLC is equipped with this unit, it can control digital quantity completely by NC method. The newly developed movement unit, even the programming language of NC skills, is also issued, which provides convenience for better digital control with PLC.
