In the application of PLC high-speed counter often encounter, counter and input pulse count pulse signal does not match, rotary encoder, grating data output is TTL level, and PLC high-speed counters are required to accept is 0-24v transmission Pulse signals, some encoders provide A+, A-, B+, B-, Z+, Z- symmetrical counter-counting pulses or provide A+, A-, B+, B-, Z+, Z in order to increase the reliability of the encoder. - Symmetrically inverted sine vector signal, but the count pulses received by the PLC high-speed counter are single-phase pulses. The user did not select the appropriate interface and gave up one of the phases (the two-phase count pulses provided to improve the system's anti-interference ability) for counting.
Another example is the application of rotary encoders and grating scales where non-uni-directional uniform motion is used. Its motion speed is fast, slow, time-moving, and time-invariant, or when motion speed is very low. If the interface does not match well, count errors are very likely to occur, and the pulse data transmission distance is slightly longer. In the pulse transmission process, the pulse waveform may be oddly changed.
There are many applications, although the count pulse frequency is not high, and ignore the PLC high-speed pulse counter to count the pulse of the edge is the rate requirements (pulse formation of rising, falling edge response speed is steep), especially in the application of line number comparison When a high encoder is running at a low speed, it may easily cause a sawtooth opening on the front and rear edges of the encoder pulse because the mechanical movement will inevitably produce subtle pulsation or the encoder has a gear in the front stage. There is also wear caused by long-term mechanical movements, so that a larger gap can also cause sawtooth openings along the edges of the coded pulses.
Interference on the industrial site is intricate, ranging from controlling the start of the site such as the stop of the motor, switching of large current contactors, phasic interference of thyristors, arc electric pulses, electromagnetic waves, etc. Complex interference groups, vertical and horizontal Electromagnetic interference is endless.
The problem is ultimately reflected in the count pulse, resulting in a parasitic glitch signal or parasitic interference pulse, and the parasitic glitch pulse has not been effectively curbed shaping. Therefore, it will inevitably lead to a series of problems such as unstable, unreliable, inaccurate count of PLC high-speed counters, cumulative errors, and occasional count errors.
Therefore, many components are perfect when they are doing simulation tests in the laboratory, but once they arrive at the industrial site, they are not normal. This is often due to ignoring the overall concept of system design, system interference caused by the mismatch between the various systems and systems. It will directly affect the PLC control accuracy, making the original set in order to improve the control accuracy, but can not play the effect of improving accuracy. That is, the theoretical design accuracy is far from the actual results. Sometimes mistakenly believe that there are problems with the quality of the PLC high-speed counter, the encoder is faulty, and the number of encoder lines is not enough.... It did not find where the original source of the problem was and was unable to start. It did not take effective measures to overcome or failed to find an effective way to overcome the interference.
To this end, we have addressed these common and common technical problems in the domestic electrical systems and industrial automation control systems. We have carefully and carefully analyzed and studied many large-scale system integration projects introduced abroad, and the relatively high degree of automation is relatively classic. The control system. It is found that there are many details that are often overlooked by our designers. They are often thought of as "superfluous" or parts that are considered to "save" the overhead. It seems that those interfaces can still work without them. It is often "concise" from the cost point of view when designing.
After analyzing and researching the "reduced redundant" interface components and then conducting field tests on the industrial site, we know that the necessity of configuring the entire system and selecting the matching interface are reliable for the long-term stable operation of the system. Protection. This is particularly important in NC projects where the accuracy of the mechanical and electrical components is relatively high. To this end, we have introduced advanced and mature technologies, absorbing and digesting many details of the processing methods. Specially designed semi-domestic MHM-02A/B double high-speed grating isolation coupler and MHM-06 dual high-speed differential mode signal converter interface. And there are also a variety of output methods, which can meet the requirements of the existing forms of PLC controllers at home and abroad. It has been verified on many PLC numerical control systems, especially on those problematic systems, and on the actual application of the old system for numerical control transformation projects. The control accuracy has been significantly improved, so that the theoretical design accuracy and the actual results are completely consistent. It is indeed "more" than "I", and it can really solve the problem and produce immediate results with twice the effort. And then look back and find out why the products of many famous brands in the world are quite different from our similar products. Comparing carefully, we really know what we are, and we don't know why it's the essence of it.
Features: FEATURES MHM-02 double high-speed photoelectric grid coupler is a good interface for high-speed data transmission of rotary encoder, grating scale and PLC controller high-speed counter module
A. MHM-02 type high-speed grating isolator (adopting advanced Blu-ray technology) can be applied between the high-speed transmission and conversion interfaces between the TTL and PLC of the microprocessor system (such as solving the problem between the Reynolds rotary encoder output and the PLC controller. Conversion interface, interface between TTL and Siemens FM350-2 high-speed counting module, Siemens 313C-2DP high-speed counting channel), conversion interface between motor digital photoelectric encoder and PLC controller, pulse signal between inverter and PLC controller The signal transmission, data input/output conversion interface, microprocessor system and computer peripheral interface are also particularly suitable for motor control applications and other fields. In particular, it can overcome the strong interference of the industrial control system in a complex field environment, electrically isolating the power transmission actuator from the remote PLC control network system, and eliminating electric interference (such as pulse-transforming and shaping) from strong electric fields and strong magnetic fields. MHM-02 high-speed optoelectronic coupling module can separate the system and effectively protect the more sensitive circuit, and has the pulse shaping function, which effectively improves the anti-interference performance between the systems. Provides a completely physically isolated security interface between high and low voltages in industrial automation control systems. Built-in two-way independent modular optical copuplers isolator
B. MHM-02 high-speed grating isolator conventional product input, there are PLC level interface 02A, TTL level interface 02B, special requirements can be customized. Output, there are push-pull type and open-collector output type 02AO, 02BO, there are fixed TTL level output 02AT, 02BT, three optional one.
C. The structure adopts a bayonet-type modular structure, which can be directly snapped into the standard rail, and is easy to install, disassemble and maintain. Multiple pieces can be compactly stacked and mounted on the standard track DIN, which saves and replaces the control cabinet input and output terminals.
Details download, welcome technical discussions and technical advice
I. Technical parameters SPECIFICATIONS
Input parameters
INPUT DATA
Operating voltage range
Operating Voltage Range
5 - 24 V
Input interface voltage type
Input Voltage
Type A is PLC level 0 - 24 V, Type B is TTL level 0 - 5V
Typical input current
Type Input Current With Un
5 mA
Typical transmission frequency
Transmission Frequency
MHM02A/B 0 - 800 KHz ,MHM-02AO/BO 0 - 500KHz
Output parameters
OUTPUT DATA
Output high
High Level Output Voltage
Normal output high is the module operating voltage minus 1V (DC)
Low output
Low Level Output Voltage
Normal output low is < 0.4V (Io = 25 mA)
Continuous load current output current
Continuous Load Current
Conventional Output 25 mA Open Collector Type 100 mA
Typical switching speed
Switch - Off Delay
0.5 us
Typical operating parameters
TYPE GENERAL DATA
Input and output isolation voltage
Isolation Voltage in / out
2500 V
range of working temperature
Operating Temperature Range
-20 - +70 °C
Note: The MHM-02AT input is PLC level, the MHM-02BT input is TTL level, the module operating power range can be DC 9 – 30 V, and the output is fixed at TTL level.
The MHM-02AO input is PLC level and the MHM-02BO input is TTL level. The module's operating power range is DC 9 – 30 V and the output is open collector OC.