Estun Servo Motors – Encoder FAQs

1. Q: What are the precautions for the selection of incremental rotary encoders?

There are three parameters that should be noted:

1. Mechanical installation dimensions, including positioning stops, shaft diameters, and mounting holes; cable outlet mode; installation space volume; Whether the protection level of the working environment meets the requirements.

2. Resolution, that is, the number of pulses output per revolution when the encoder is working, whether it meets the design accuracy requirements.

3. Electrical interface, encoder output mode commonly includes push-pull output (F type HTL format), voltage output (E), open collector circuit (C, common C is NPN type tube output, C2 is PNP type tube output), long-line driver output. The output mode should match the interface circuit of the control system.

2. Q: How to use incremental encoders?

1. Incremental rotary encoders have a difference in resolution, using the number of pulses generated per revolution to measure, the number of pulses from 6 to 5400 or higher, the more pulses, the higher the resolution; This is one of the important bases for selection.

2. Incremental encoders usually have three signal outputs (differential has six signals): A, B and Z, generally using TTL level, A pulse in the front, B pulse in the back, A and B pulses are 90 degrees apart, and each revolution emits a Z pulse, which can be used as a reference mechanical zero. Generally, A ahead of B or B ahead of A for direction judgment, our company's incremental encoder is defined as the shaft end of the encoder clockwise rotation for forward rotation, A ahead of B is 90 °, on the contrary, counterclockwise rotation is reversed B ahead A is 90 °. There are also differences, depending on the product description.

3. Use PLC to collect data, and high-speed counting module can be selected; Use the industrial computer to collect data, and you can choose a high-speed counting board card; To use a microcontroller to collect data, it is recommended to use an input port with a photocoupler.

4. It is recommended that the B pulse be the forward (forward) pulse, the A pulse should be the reverse (backward) pulse, and the Z origin zero pulse.

5. Set up a counting stack in the electronic device.

3. About outdoor use or use in harsh environments

The equipment is used in the field, the on-site environment is dirty, and the encoder is afraid of being damaged.

There are aluminum alloy (stainless steel can be made of special requirements) sealed protective shell, double bearing heavy-duty encoder, placed outdoors not afraid of dirty, steel mills, heavy equipment can be used.

However, if there is space for the encoder installation part, it is recommended to install a protective shell outside the encoder to strengthen its protection.

4. From proximity switches, photoelectric switches to rotary encoders:

The positioning in industrial control, the application of proximity switches and photoelectric switches has been quite mature and very easy to use. However, with the continuous development of industrial control, there are new requirements, so that the application advantages of using rotary encoders are highlighted:

Informatization: In addition to positioning, the control room can also know its specific location;

Flexible: The positioning can be flexibly adjusted in the control room;

Convenient and safe on-site installation, longevity: a fist-sized rotary encoder can measure the interval from a few μ to tens or hundreds of meters, n stations, as long as the safety installation of a rotary encoder is solved, it can avoid many proximity switches, photoelectric switches in the field of mechanical installation troubles, easy to be damaged and troubled by high temperature, water vapor and other problems. Since it is a photoelectric code disc, there is no mechanical loss, and as long as the installation position is correct, its service life is often very long.

Multi-functional: In addition to positioning, it can also transmit the current position remotely and convert the movement speed, which is especially important for applications such as inverters and stepper motors.

Economy: For multiple control stations, only the cost of one rotary encoder is required, and the more important installation, maintenance, and loss costs are reduced, and the service life is increased, and its economy is gradually highlighted.

As mentioned above, rotary encoders have been more and more widely used in various industrial control applications.

5. About power supply and encoder and PLC connection:

Generally, there are three working power supplies for encoders: 5Vdc, 5-13Vdc or 11-26Vdc. If you buy an encoder with 11-26Vdc, you can use the 24V power supply of the PLC, it should be noted that:

1. The current consumption of the encoder is within the power supply power range of the PLC.

2. If the encoder is a parallel output, connect the I/O point of the PLC, you need to know whether the signal level of the encoder is a push-pull (or push-pull) output or an open-collector output, if it is an open-collector output, there are two types: N type and P type, which need to be the same as the I/O polarity of the PLC. If it is a push-pull output, there is no problem with the connection.

3. If the encoder is the driver output, the general signal level is 5V, be careful when connecting, do not let the 24V power level into the 5V signal wiring and damage the signal end of the encoder. (Our company can also do wide voltage driver output (5-30Vdc), there is this requirement to indicate when ordering).

Estun Servo Motors – Encoder FAQs

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