Some introductory remarks on the encoder

1: Selection of incremental rotary encoder which Note: 1. Armed installation dimensions, including location only the mouth of the shaft diameter, the installation holes; cable outlet way; installation space volume; work environment protection rating meets the requirements.

2. Resolution, that is, the work of each encoder output pulse lap number, is designed to be used to meet the required precision.

3. Electrical interface, the encoder outputs are push-pull output common mode (F-type HTL format), voltage output (E), open collector (C, common C for the NPN-tube output, C2 for the PNP-tube output), long-term driver outputs. A manner that its output and its control system interface circuit match.

2 How to use an incremental encoder? 1, incremental rotary encoder with resolution of differences, using the number of pulses generated by each lap to measure the number from 6-5400 or higher, and pulse a few more higher the resolution; this is an important basis for selection of one.

2, incremental encoders are usually three-way signal output (differential and six-channel signal): A, B, and Z, generally use the TTL-level, A pulse in the former, B pulse in the post, A, B pulse difference of 90 degrees, each Circle issued a Z pulse can be used as reference to machine zero. Ahead of the general use of A or B to B ahead of A to contracting, our company is defined as the incremental encoder shaft encoder clockwise to see a positive change, A ahead of B is 90 °, the other hand anti-clockwise rotation for the reverse B ahead of A is 90 °. There are not the same, look at product description.

3, using PLC data collection may make use of high-speed counting module; the use of IPC data collection may make use of high-speed counting board; the use of microcomputer data acquisition, the proposed use with optical coupler input port.

4, the proposed B-pulse becoming obedient to the (forward) Pulse, A pulse did reverse (backward) pulse, Z origin of zero pulse.

5, set up in the electronic device counts the stack

3: from proximity switches, photoelectric switches to the Rotary Encoder: industrial control positioning, proximity switches, photoelectric switches application has been quite mature, and it just works. However, with the IPC continues to develop, there has been new requirements, so that the application of rotary encoders use advantages of the highlights:

Information: In addition to positioning, the control room can also be aware of their specific location;

Flexible: Positioning in the control room flexible adjustment;

On-site installation of convenience and safety, longevity: fist the size of a rotary encoder, can be measured from several μ to dozens, hundreds of meters distance, n a working position, as long as a rotary encoder to solve installation problems of security, you can to avoid a lot of proximity switches, photoelectric switches installed in the field machine trouble, was damaged and was easy to heat, water, gas trouble and other issues. Because it is optical encoder, no mechanical wear and tear, as long as the installation location accuracy of their service life is often very long.

Multi-function: In addition to location, you can also FET current position, velocity conversion for the inverter, stepping motor applications such as particularly important.

Economic-oriented: For multiple control stations, only the cost of a rotary encoder, and more the main installation, maintenance, loss, cost reduction, service life of growth, its economy based increasingly to the fore.

4: Power supply and encoder and PLC connection: General encoder Power Supply There are three: 5Vdc ,5-13 Vdc or 11-26Vdc. If you are buying Encoder is 11-26Vdc, and can use PLC's 24V power supply, take note:

1. Encoder current consumption, in the PLC, Power range.

2. The case of parallel output of the encoder to connect PLC's I / O points, need to know the encoder signal level is a push-pull (or push-pull) output or open collector output, the case of open-collector output, there are N-type and P-type two, the need and the PLC, I / O polarity of the same. The case of push-pull outputs to connect without any problems.

3. Encoder case of driver output, the general signal level is 5V, and the connection time to be careful not to let the 24V power supply into the 5V level string signal wiring damage to the end of the encoder signals.

5: Interference caused by bad wave, resulting in count are not allowed. How to judge? The encoder is a precision components, mainly because of the encoder around the more serious interference, such as: whether there are large electric motors, electric welding machine caused by frequent start-interference, whether the same pipeline and power line transmission.

Choice of what kind of output to the interference is also very important, the general output signal with interference better than the reverse, namely, A ~ A-, B ~ B-, Z ~ Z-, is characterized with the power eight lines, while the than five lines (a total of zero). With a reverse signal in the cable transmission is symmetrical, a small disturbance in the receiving device can also be an additional judge (for example, the signal receiving equipment, the use of A, B signal 90 ° phase difference, read the level of 10,11 , 01,00 four kinds of condition, counted as a valid pulse, this program can effectively improve the system anti-jamming performance (an accurate count)).

Is the encoder also has good and bad, its encoder \ electronic chip \ internal circuit \ signal output vary considerably, which is why a 1000-line incremental encoder from 300 yuan to 3,000 yuan in the reasons for the difference. ① exclusion (relocated, closed, isolated) interference sources, ② to determine whether the cumulative gap for the mechanical errors, ③ to determine whether the control system and the encoder circuit interface does not match the (encoder selection error); ① ② ③ Method else is even trying after the failure the phenomenon of exclusion, may be a preliminary judge, If you do not rule out the need for further analysis.

Encoder to determine whether a simple method is own fault exclusion. Exclusion of the specific method is: the same model with a single encoder to replace up, if the failure phenomenon of the same can basically rule out the possibility encoder failure, because there are two encoders at the same time a small probability of failure events may be small, you can considered as 0. If the same model encoders replace it up, breakdown phenomenon at once removed, can be found is the basic encoder failure.

6: What is long-term drive? Common type encoder can telematics? , Also known as Differential Line Driver Line Driver, 5V, TTL positive and negative waveform symmetry, because of its positive and negative current in the opposite direction, to offset the external electromagnetic field, so anti-interference ability.

Common type encoder general transmission distance is 100 meters, if it is 24V HTL-type and there is a negative signal symmetry, the transmission distance of 300-400 meters.

7: rotary encoder detecting linear displacement method? 1, the use of "flexible Couplings" will be driven rotary encoders and linear displacement of the power unit directly linked spindle axis.

2, using a small gear (spur gear, bevel gear or worm gear) box in conjunction with the power unit shaft.

3, using the straight rack gear to pass on a rotating linear displacement information.

4, in the transmission chain sprocket on a straight-line displacement to obtain the information.

5, in the synchronous belt wheel gain linear displacement information.

6, using the rotating wheel equipped with magnetic linear displacement encoder in the formation of the steel surface to obtain displacement information (to avoid the slip).

7, using a similar "steel tape measure," "may retracting wire assembly" Connect rotary encoder to detect linear displacement information (data processing required to overcome the stacked winding error).

8, similar to 7, using a small torque motor with a "retractable steel wire assembly" Connect rotary encoder to detect linear displacement information (currently in Germany, a similar product, complex structure, almost no laminated winding error)

8: Incremental Grating Z signal can be used as zero? Radial grating encoder How to choose?

Both linear grating or its Z-axis encoder signal can reach with the A \ B the same accuracy as the signal, only one shaft encoder is a circle, while the straight-line grating is a certain distance intervals, with the signal can reach a very a high repeatability. Can first close switch with ordinary first position, and then find the closest Z-signals (each in the same direction to find), filled with hope when the do not forget its phase modulation and phase grating line, otherwise not allowed.

Segmentation accuracy based on your requirements, and resolution requirements selection. High precision, naturally choose a week-lined high accuracy is not high, there is no need to choose the number of high-lined circular grating encoder has.

9: incremental encoder and absolute encoder What's the difference? Servo system how to make a choice? Commonly used for the incremental encoder, if the right position, the stringent requirements of zero-bit absolute-type encoder. Servo system to a specific analysis to see applications.

Measuring the speed with commonly used incremental encoder, unlimited accumulation measurement; measuring absolute position encoder, the location and uniqueness (single ring or multiple ring) with a final look at applications to see to achieve the purpose and requirements.

10: absolute type rotary encoder selection of attention, rotary encoders and proximity switches, photoelectric switches advantage of comparison: absolute encoder lap 8 from the economy to high-precision 17, the price from several hundred dollars to more than 1 trillion range;

The majority of multi-turn absolute encoder with 25-bit, output has SSI, bus, Profibus-DP, Can L2, Interbus, DeviceNet, the price is also available from more than three to more than 1 range.

Rotary optical encoder measuring the angle and length, is already a very mature technology, and today a large number of range then the high-precision absolute-type encoder, greatly increased the accuracy and reliability, but also economical and practical. For now, it is still is a measure of the length of the maximum choice.

11: from an incremental encoder to the absolute encoder: rotary incremental encoder to rotate when the output pulse, through the counting device to know its location, when the encoder is not fixed or a power outage, the device's internal memory to rely on counting to remember the location. Thus, when the power failure, the encoder can not have any movement, when the phone work, the encoder output pulse process can not be lost of interference pulse, otherwise the count will be offset zero memory devices, and this partial the amount of shift is not know, only the production of errors be known until after the outcome.

The solution is to increase the reference point after the encoder for each reference point, a reference location of the amendment into the counting device memory locations. In the reference point before, we can not guarantee the accuracy of the location. To this end, the IPC will have to go first to a reference point for each operation, the boot Keep the change and other methods. Optical encoder absolute encoder that there are many Road groove, each groove followed by a 2 line, 4 lines, 8 lines, 16 lines. . . . . . Arranged, so that every one in the encoder position, by reading the line Every moment pass, dark, get a group from two to two zero-th power n-1 th power of the only two binary code ( Gray code), which is called n-bit absolute encoder. This encoder is a mechanical position by the encoder decide, it is not power failures, interference effects.

Absolute encoder determined by the mechanical position of the uniqueness of each location, it did not have memory, without the need to find a reference point, and do not always count, and when you need to know the location when the position went to read it. In this way, the encoder anti-jamming features, the reliability of data is greatly enhanced.

As the absolute encoder positioning in the location is obviously superior to incremental encoders, has been increasingly applied to industrial control positioning.

Measurement speed can be infinitely need to accumulate measurement, the current incremental encoder in speed applications are still in no position to replace the mainstream.

12: Using the absolute encoder should pay attention to what matters?

I). Mechanical parts:

1. Measuring length and angle measurement, the measured length of how mechanical conversion (there are some in the above description, such as the call is not clear to discussion). Measured angle is 360 degrees inside the (single circle), or may be too 360 degree (multi-turn). The direction of the production process is a rotating cycle to work, or back and forth direction of the work cycle.

2. Shaft connected to install the form, there are axial coupling through the soft link, or sleeve-type connections.

3. Use of the environment: dust, water vapor, vibration, impact?

(B) Electrical parts

1. Connect the output of receiving part of that?

2. Signal form?

3. Resolution requirements?

4. Control requirements?

12: From the single-ring absolute encoder to the multi-turn absolute encoder: rotary single-ring absolute encoder to measure the optical code disk rotating the Road engraved lines in order to obtain a unique code, when more than 360-degree rotation When encoding back to square one, so that is not consistent with the principle of absolute encoding only, so that encoders can be used only within a 360-degree rotation range of measurement, known as the single-ring absolute encoder.

If you want to rotate over 360 degrees range of measurement, it is necessary to use multi-turn absolute encoder.

Encoder manufacturers to use the principle of mechanical clock gears, when the center encoder rotation, through another set of gear transmission encoder (or group of gear, multiple sets of code plate), in a single lap on the basis of coding to increase the number of laps coding, in order to expand the scope of the encoder measurement, so that the absolute encoder is called multi-turn-type absolute encoder, which is also determined by the mechanical position code, the only non-duplication of code for each location, without memory.

Another advantage of multi-turn encoder is due to measuring range, the actual use is often more affluent, so that unnecessary struggling to find zero installation will be an intermediate position can be as a starting point, while greatly simplifying the installation and debugging more difficult.

Multi-turn-type absolute encoder positioning in the length of the obvious advantages, has become increasingly applied to industrial control positioning.

13: absolute-type encoder serial and parallel output information: the absolute encoder output is a number of digital (Gray code or pure binary code), parallel output interface is a little more high-low output, in order to on behalf of digital 1 or 0, for the median absolute encoder is not high, the general form of the output directly as a digital, direct access to PLC or host computer's I / O interface, the output immediately, the connection simple. But the parallel output of the following questions:

1. Must be a Gray code, as the case of a pure binary code, refresh the data may have a number of changes, readings will result in the wrong code in a short time.

2. All interfaces must ensure that the connection is good, because if the individual connection bad point, the point potential is always 0, resulting in the wrong code can not be judged.

3. Transmission distance can not be far, usually 12 meters, for complex environments, preferably isolated.

4. For more digits, to many-core cable, and to ensure that the connection quality, and the resulting difficulty of engineering, the same for the encoder to the same time, there are many nodes in the output to increase the failure rate of the encoder failure.

Parallel: timing, the data also issued; space, each digit of data with the occupation of a cable.

Incremental encoder output is usually parallel output.

Serial output:

Serial output is through the convention, in time, there has a data output, such an agreement known as the communication protocol, which connect the physical form of RS232, RS422 (TTL), RS485 and so on.

Less serial output cable, transmission distance, for the protection and reliability of the encoder will be greatly increased, the number of general high absolute encoders are serial output.

As the absolute encoder of some well-known manufacturers in Germany, so most of the serial output is supporting Germany's Siemens, such as synchronous serial output SSI, PROFIBUS-DP bus type is the output and so on.

Serial output encoder to connect Germany's Siemens equipment is relatively easy, but non-German line connecting the equipment, the interface is the problem, and I offer a variety of interface output devices, can solve this problem.

Serial: time, the data in accordance with convention, there are successively; space, all the data bits are in a group of cable on the (order) issued.

14: Serial Encoder should all be absolute it? Serial is defined as the time agreed, serial output digital code signals, the basic is absolute, but there are also some incremental encoder, through the built-in battery memory of the origin, its You can also place the serial output value, such as the battery cable is not associated or incremental encoder, this is also known as pseudo-absolute encoder, servo system in a number of Japan's more, see. In fact, by its very nature, or an incremental encoder.

15: Why is "an absolute encoder"? "Absolute encoder," as opposed to "incremental encoder" is concerned.

"Absolute encoder," expressed in some way, and remember to use an object's absolute position, angle and number of laps. That, once the position, angle and circle the number of fixed, when the encoder values are indicated only a fixed, including the electricity blackouts after the vote. "Incremental encoder," can not do this. General "incremental encoder" output 2 A, B pulse signal, and a Z (L) the zero bit signal, A, B pulse in each 90-degree phase angle difference. By pulse counting can know position, angle and circle the number of increments, through the A, B pulse signal advance or delay can know the direction of power failure, you must start again from the agreed baseline count. , "Incremental Encoder" for position, angle and circle the number of post-processing needs to be done to re-cast power to do, "re-zero" operation, therefore, "Incremental Encoder" than "absolute encoder" in cheaper price许多.

16: photoelectric encoder, optical electronic scale and static magnetic gate advantages and disadvantages of an absolute encoder? 1 advantages: small size, precision, their degree of resolution can be high, non-contact wear-free; the same species, can detect angle displacement, but also help in the mechanical conversion devices detecting linear displacement; multi-turn absolute optical encoder can detect very long-range straight-line displacement (eg, more than 25 laps). Long life, installation free, the interface forms a rich, reasonable price. Mature technology, many years ago is widely used at home and abroad.

2, disadvantages: Precision but for outdoor and harsh environments offer higher protection requirements; measuring linear displacement is dependent on plant transformation, the need to eliminate the error caused by mechanical clearance; detection of objects in orbit is difficult to overcome the slip.

Optical electronic scale:

1 advantages: precision, their degree of resolution is high (up to 0.005mm); volume is moderate, direct measurement of linear displacement; non-contact wear-free measuring broad gap; an affordable price, the interface forms a rich, has metal-cutting machinery industry in China and abroad get more applications (such as wire cutting, EDM, etc.).

2, disadvantages: Measuring straight line and angle to use a different species; range was limited (range of more than 4m, expensive manufacturing problems), not suitable for a large number of processes in the harsh environment at the implementation of displacement detection.

Gate absolute static magnetic encoder:

1 advantages: Volume is moderate, direct measurement of linear displacement, the absolute number of coding theory, there is no range restriction; non-contact-free wear, anti-poor environment, can be 1,000 meters underwater use; interface, the form of rich, diverse measurement methods; prices still capable of receiving .

2, Disadvantages: resolution is not high degree of 1mm; measuring lines and angles to use a different species; not suitable for a small office in the precise implementation of the displacement detection (greater than 260 millimeters).

17: absolute encoder how to find the origin? 50 locations targeting a 360-degree uniform Dividers do?

Encoding the absolute encoder is a power of 2-th power, there is no 360-degree uniform 50 equal portions, and to approximate to see how high precision, the election how high the number of encoder lines, if the accuracy requirement is not too high, with 8-bit 256-line on it. Encoder, each location has a unique encoding, zero can be used as zero, zero, can also be defined at any position, other positions compared with the calculation.

If you can use a reference point, then can also be incremental, and due to slow, it should be 3000 or more lanes in the election, each circle a zero.