Key word: encoder applications
A selection of incremental rotary encoder what note?
Three aspects should be paid attention to the parameters:
1 gave installation size
Including positioning the mouth, trunnion, installing hole a; Cable outlet way; Installation space volume; Work environment protection grade whether meet the requirements.
2 resolution
That is when the work each lap output encoder the number of pulses, whether meet the design using accuracy.
3 electrical interface
Encoder way has push-pull output common output (F type HTL format), voltage output (E), open collector (C, common C for NPN type pipe output, C2 type pipe for PNP output), long term driver output. With its output way of the control system interface circuit match.
2 how to use the incremental encoder?
1 increment rotary encoder resolution have differences, use each lap produce the number of pulses to measurement, from 6 to 5400 the number or higher, pulse, more the higher resolution; This is one of the important criteria for selection.
2 increment encoder usually has three road signal output (difference have six signal) : A, B and Z, generally USES the TTL level, A pulse in the front, and B pulse of the, A, B pulse differ 90 degrees, each lap send A Z pulse, and can be used for reference to zero. On average, A leading B or advance on to A to B.
3 use PLC data collection, can choose the count module; In the industrial automation now, use industrial computer data collection, can choose the count interface card; Using single chip microcomputer data collection, the proposal is chosen with photoelectric coupler input port.
4 suggest B pulse do downstream (to) pulse, A pulse do reverse (to) pulse, Z origin zero pulse.
5 in electronic devices in establishing the count stack.
Three power supply and encoder and about PLC connection
General encoder work power have three: 5 Vdc, 5-13 Vdc or 11-26 Vdc. If you buy of the encoder USES is 11-26 Vdc, can use PLC 24 V power supply, need to pay attention to:
1 encoder power flow, the power supply in PLC power range.
2 encoder so parallel output, connecting the PLC I/O point, need to understand the encoder signal level is push-pull type (or says the push-pull type) output or open collector output, so open collector output, N type and P type two kinds, and to the PLC of I/O same polarity. So push-pull type output is connected no questions.
3 encoder so driver output, general the signal level is 5 V, connection to be careful, don't let 24 V power level 5 V series with the signal wiring and damage of the encoder to the signal. (our company also can do the wide voltage driver output (5-30 Vdc), there is the requirement to indicate the order)
Four in many circumstances and no bad example is, but the cause of the interference, causing the wave pattern is bad, not to count. Ask how to judge?
Encoder is precision components, and this mainly because encoder is more serious interference around, for example: whether to have large motor, electric welding machine frequent starting cause interference, and whether the same pipeline transmission power lines, etc.
Choose what kind of output against interference is very important also, general output with reverse signals of anti-disturbance better, that is A +-A-B +-B-Z +-Z-its characteristic is coupled with power 8 lines, not five line (of zero). Take the reverse signals in the cable transmission is symmetrical, little interference in receiving equipment can also add in judgment (for example to accept the signal equipment using A, B signal 90 ° phase difference, and read level 10, 11, 01, 00 four state, plan for A pulse, the project can effectively improve the system anti-jamming performance (counting accurate)).
Is there are good encoder, the code salver electronic circuit inside the chip signal output of the difference is very big, or how a 1000 line increment encoder will be 300 yuan to 3000 yuan from difference so big?
(1) removed (move away from, closing, isolation) interference sources
(2) the judge whether for mechanical clearance accumulative total error
(3) to determine whether for control system and encoder interface circuit does not match (encoder selection error);
(1) (2) (3) method after attempting to rule out fault phenomena, the preliminary judgment, if not ruled out should be further analysis.
Judge whether the fault of their own for encoder simple method is PaiChuFa. The specific method PaiChuFa is: with a same model encoder replace up, if the fault the same phenomenon, but the basic rule out is encoder failure problems, because of two encoder and the fault of small probability events happen is probably small, can see as 0. If change a same model encoder up, fault phenomenon immediately ruled out, can be basic fault judgement is encoder.
5 what is long term drive? Regular encoder can long distance transmission?
Long term drive also called difference long term drive, 5 V, the positive and negative waveform TTL symmetrical forms, because the positive and negative current direction instead, external electromagnetic field offset, the anti-interference ability is strong.
Regular encoder transmission distance is 100 meters commonly, if is 24 V HTL type and have symmetrical negative signal, the transmission distance 300-400 meters.
Six simple spin encoder can introduce the method of linear displacement detection?
1 use "elastic coupling implement" will rotary encoder and the drive of the power equipment of the linear displacement of main shaft coupling directly.
2 use small gears (straight tooth, umbrella teeth or worm gear and worm) box and power device coupling.