RS422 applies mediumly in net of couplet of numerical control machine tool

The article elaborated RS422 to use a method mediumly in communication of numerical control machine tool, provide network of a kind of simple, reliable, economic couplet of numerical control machine tool method. Numerical control machine tool is collect computer technology, automata technology, mechanical production technology the child at an organic whole; It is implementation flexible production main unit. The machine program that numerical control machine tool can create with CAD, CAM directly machines mechanical spare parts. The machine program of complex and mechanical spare parts often very giant. The control system that inputs numerical control machine tool through RS232 interface by the computer normally -- CNC. As a result of RS232 oneself characteristic, transmission distance is not long, in factory environment, put in complex interference, although use shorter connect a line, often also pass output fault, cannot transmit even. Machine program data makes mistake, can bring about treatment spare parts to discard as useless not only, still can make the machine tool is destroyed sometimes. Solve afore-mentioned problems, can transmit RS232 means instead RS422 to transmit means. RS422 transmits means to reduce data to be piled up by accident greatly, lengthen communication distance, can realize machine tool of much stage numerical control to share a computer.  1 RS232 and RS422 RS232 are a PC (PC) the standard is serial communication interface. RS232 standard sets, driver allows the capacitance load of 2500pf, communication is apart from the limitation that is set by this. RS232 belongs to sheet to carry signal to transmit (see a picture 1) , put in in all noise to mix cannot restrain in all the model disturbs a problem, create news report fluky. Putting in the environment of strong interference source, fluky problem is highlighted particularly. Signal of graph 1 RS232 transmits graph RS422 is arrive for a few meters in communication distance when a few kilometre, the communication means of the full duplex operation that uses extensively. RS422 is to use a balance to send, the way that poor cent accepts, use double skeining thread of two pairs of screen to join (see a picture 2) , because this is had,restrain in all the ability that the model disturbs. Accept appliance to have very tall sensitivity, can detect low the voltage that amounts to 200mV, so transmission signal can be in very far place to get resumptive. Signal of graph 2 RS422 transmits a graph the join that 2 individual CNC and PC pass RS422 2.

1 hardware joins most CNC system has RS422 interface, but go up in box of CNC built-in control or control plate, did not connect a machine tool on exterior box. This RS422 interface can search to be used directly. PC does not have RS422 interface commonly, can have RS422 interface through buying board have expansion, also can do to turn receive board, realize the RS232 changeover to RS422. The commutation of RS232 of use MAX202 implementation to TTL n (3) seeing a picture, MAX202 interior has circuit of power source commutation, use onefold + 5V power source can realize the RS232 commutation to TTL n; Use MAX490E to realize TTL to the changeover of RS422 signal, MAX490E has ± 15KV ESD protection, can prevent chip of mouth of electrostatic butt joint effectively destroy. Add install interface board to be able to protect PC RS232 interface effectively not to suffer unexpected damage. Electric current of interface board job is very small, power source can be obtained from the USB mouth of PC. Graph 3 use MAX202 realize RS232 to pursue to TTL n commutation 2.

2 software install CNC to a lot of parameter are used at controlling communication. Connect a line to decrease, circuit does not have line of join hardware handclasp, answer so CNC and handclasp of software of instead of PC handclasp means (means of XON, XOFF) ; Because capability of RS422 interference rejection is very strong, can set communication baud rate highest value, raise communication rate; Input CNC data the mouth (Input Device) instead RS422. PC software also is made adjust accordingly, keep as consistent as CNC. When many 3 CNC and PC have much stage CNC through the join of RS422, can impose a plan in the every RS232 interface of PC 3 turn receive board implementation and CNC join, general PC has 2 RS232 interface only, can join only two CNC, PC utilization rate is very low. To the graph 3 turn receive board make it is OK to be revised certainly implementation strings together a mouth to join much stage CNC(sees graph 4) with. The graph strings together mouth and graph of join of much stage CNC 4 to adopt a plan 4 turn receive board, can realize a join that strings together mouth and 4 CNC. This kind of join is restricted exclusively is PC can time-sharing and different CNC communication. Graph 4 in the CNC that does not undertake data is transmitted strings together an output to be 1 (when CNC does not switch on the mobile phone, by on pull, next pulling resistor makes sure the output that need branch is 1) , with the CNC signal get along with that transmitting output remains the CNC signal that transmitting, the CNC signal that transmitting accordingly can send PC. When PC sends signal, all CNC can accept the data that conveys to PC, but the CNC that is not in data to transmit condition will discard automatically the data that PC hair comes to. If need link more CNC, can according to afore-mentioned principles, increase to have expansion with the door and MAX490E. Software setting is similar to only station join. Most PC transmits software to all can make different setting in the light of different CNC, in saving a file. Transfer into different setting file, can come true to make different setting to stringing together a mouth, accordingly although use same it is OK still to string together a mouth make different parameter install to different CNC. 4 last words of  can come true to join with much stage CNC with a PC, the couplet net pattern that changed machine tool of every numerical control to must distribute a computer, offerred way of net of couplet of a kind of cheap and effective CNC. RS422 transmission means allows longer of the distance transmit, workshop of every CNC Machining should be deployed only arrive 2 computers can satisfy need. The computer passes a local area network to be able to join with other computer and workstation, transmit on net of machine program of implementation spare parts not only, and those who realized the resource such as machine program of CAD, CAM, spare parts share. CNC Milling