1. The number compares a system form a number to compare a system to be able to comprise by 6 main link at most (5-38) seeing a picture: (The command signal that 1) provides by numerical control device. It can be digital signal, also can be pulse number signal. (2) is believed by the place of machine tool workbench that measures component to offer date. It can be digital signal, also can be digital pulse signal. (3) is finished command signal and measure feedback signal relative comparator. (The mutual changeover component of signal of 4) number pulse and number. Its according to the property of the function of comparator and command signal and feedback signal decision accepts or reject. (5) drive carries out component. It drives machine tool workbench to move according to the output of comparator. The system is compared in the number in, commonly used position measures feedback component to have grating and code dish. Former those who offer is digital pulse alignment, latter is digital signal. Although also can use what can generate imitate feedback signal measure component in this kind of system, if rotate synchronized of transformer, induction, but should pass modulus (A/D) changeover, after measuring word of amount to of imitate quantitative change, ability provides a system, such meetings raise complex rate of the system, the number in the model uses reason rarely in the system quite. Graph 5-38 number compares the digital comparator with systematic commonly used composition to have 3 kinds roughly: Number and digital comparator, digital pulse comparator, digital pulse comparator. Because instruction and feedback signal are differ,can fit relative need surely, accordingly, between instruction and comparator and feedback and must increase sometimes between comparator " digital pulse, the number is changed " circuit. The output of comparator reflected the poor cost of command signal and feedback signal, and the direction of poor value. After this one output signal magnifies, control carries out component. Executive component can be motor of servo of servo electric machinery, hydraulic pressure. A specific figure compares a system, according to command signal and the form that measure feedback signal, and the form of the comparator of the choice, can be a system that includes 6 afore-mentioned shares, also can comprise by among them some a few parts only. 2. The pulse of number of 1) of main function component that the number compares a system, digital converter (changeover of 1) number pulse is a number. To number of digital pulse translate into, its simple implementation is a reversible tally, it has the pulse of the input count, be worth output with the number. The demand that piles up a form according to logarithm is diverse, reversible tally can be a binary system, 2, decimal or the tally of other type, graph 5-39 is by two 2, the digital pulse that decimal tally comprises, digital converter. The circuitry of number of translate into of pulse of graph 5-39 number (pulse of word of amount to of 2) number changeover. To pulse of number of digital translate into, have two kinds of methods commonly usedly. The first kind of method is the line that introduces subtration tally composition, if graph 5-40 place is shown, the digital place that will change first enters subtration tally, after Zhong Maichong CP comes at that time, make subtration tally makes subtration computation on one hand, enter on the other hand with the door. The content that is like subtration tally is " 0 " , this CP pulse is passed output with the door, the content that is like subtration tally turns into " 0 " , be shut with the door, CP pulse cannot be passed. Tally from begin computation to arrive decrease for " 0 " . Just join the number in tally with buy equivalent digital pulse from output with the door, implemented a number thereby, the changeover of digital pulse. The 2nd kind of method is to use multiplier of a pulse, ever had introduced when discussion interpolation principle, the binary number translate into that digital pulse multiplier will input namely essentially is equivalent pulse several output. Its sketch map is shown like graph 5-41 place. The 2) comparator of circuitry of pulse of number of translate into of graph 5-41 number is in one of circuitry of pulse of number of translate into of graph 5-40 number the number compares a system in, use comparator has a variety of structures, according to its the function can divide it is two kinds: It is digital comparator; 2 it is digital pulse comparator. In digital comparator, relative it is two numbers signal, and output can be qualitative, point out only namely join relative number who is big who is small, also can be ration, point out join relative number who is big, mostly little. In digital pulse comparator, commonly used method is the reversible tally that contains reversible loop. CNC MillingCNC Machining