【正文】 es various NC tasks by time173。processor on duty of controlling and occupying the system bus, while the others cannot occupy the system bus and cannot access main memory. ? This architecture is simple and can be implemented easily, whereas, for reason of centralized controlling, its performances and abilities are limited by the byte length, data width, address ability, and calculating speed of microprocessor. 《 NC Technology 》 E－ mail: .Multi173。distributed system216。 bus based multi host microprocessor system. 《 NC Technology 》 E－ mail: .Distributed system216。work munication technology 《 NC Technology 》 E－ mail: . Master173。servant system A processor is called master microprocessor, others are servant microprocessors, and they are all independent systems. Only master microprocessor can control the bus, access the resources attached with the bus, control and monitor servant microprocessors, and coordinate the operations of servant microprocessors. 《 NC Technology 》 E－ mail: .Bus based multi CPU system 《 NC Technology 》 E－ mail: .Special purpose architecture CNC units of this architecture are designed and manufactured by different enterprises respectively. They have convenient layouts, pact structures, and high performances for special purpose, but have no general characters。B system (American) are of this architecture 《 NC Technology 》 E－ mail: .Personal puter architecture 216。SIEMENS (German)216。 ALLEN173。B) 216。Blue173。User software is also called part program, which is programmed and inputted by using numerical control language (such as APT) to indicate the machining procedure of the part. It is piled into a program with various G173。codes arranged according to the process sequence. 《 NC Technology 》 E－ mail: .System software CNC system software can be sorted into two packages: managing software and control software.《 NC Technology 》 E－ mail: .The function of control software (1) Compiling the part codes inputted by users After receiving the part codes, piler will translate, trim and store them into a specified format。binary transitions to coordinate data。s center path considering the offset of tool radius。calculate some constants that will be used in interpolation calculation and speed control process, etc. 《 NC Technology 》 E－ mail: .The function of control software (2) Interpolation calculations Interpolation calculation subroutine has the same functions with hardware interpolator in NC system,!, e. ,to assign electrical pulses for axes. It is a strict real time program, and demands as less as possible number of instruction codes, that is to say, to shorten the time for performing interpolation calculations ,because the time is determinative to the feed speed of interpolation. In some CNC system ,it is adopted to bine rough interpolation and fine interpolation 《 NC Technology 》 E－ mail: .The function of control software(3) Tool pensation All types of CNC machine tools require some form(s) of pensation, such as tool length pensation, cutter radius pensation, and tool nose radius pensation. Though applied for different reasons on different machine types ,all forms of pensation allow the CNC user to allow for unpredictable conditions related to tooling. Generally speaking, if the CNC user is faced with any unpredictable situations during programming, it is likely that the CNC control manufacturer has e up with a form of pensation to deal with the problem.《 NC Technology 》 E－ mail: .The function of control software(4) Speed control 216。 While there is an unexpected abrupt changing in velocity during machining, the speed control subroutine should automatically speed up or slow down the velocity to avoid pace loss in drive system. 216。 Position control is in the position loop of servo system. 216。 position control software can usually adjust the magnification of the po