Industrial telemetry sensors

The industrial telemetry sensor application uses Motorola's encoder MC145026 and decoder MC145027. MC145026/27 is a paired chip produced by Motorola for communication. It is a low-voltage CMOS codec device widely used in remote control and telemetry circuits

　　The characteristics of industrial telemetry sensors are:

(1) When the encoder sends pin TE (pin 14) to ground (low level), the encoder outputs a series of 5-bit address and 4-bit data in different pulse encoding methods. Each time it sends, the encoder automatically sends two identical address and data pulse trains (output from pin 15).

(2) After receiving the * pulse signal sent by the encoder, if the 5-bit address of the decoder is the same as the 5-bit address * of the encoder, the 4-bit data transmitted will be sent to the register; After receiving the second pulse signal and conducting a second verification, if the address is correct and the data matches * times, the 4-bit data will be sent to the output terminal and latched; The VT pin changes from low level to high level, indicating the received signal. This high level remains until there is a new data input or a time interval of 4 data transfers without any new data input.

(3) The time required for each transmission depends on the operating frequency of the internal oscillator and is determined by the external RC parameters. The oscillation frequency can be selected within the range of 1.71-362KHz.

(4) The static current is particularly small, the encoder is less than 1uA, and the decoder is generally less than 100uA.

The system adopts the microcontroller AT89S53 to complete the timed acquisition, calculation, error processing, storage, and data transmission control of the required measured parameters. AT891553 is a low-power, high-performance CMOS 8-bit microcontroller with 12k bytes of ISPD serial programming and flash read-only program memory that can be repeatedly erased and written 1000 times. The chip integrates a general-purpose 8-bit central processing unit and ISP Flash storage unit. The powerful microcomputer AT891553 can provide a cost-effective solution for many embedded control application systems.

The microcontroller is designed and configured with an oscillation frequency of 0Hz and a power-saving mode that can be set through software. In idle mode, the CPU pauses while the RAM timer counter, serial port, and external interrupt system can continue to operate. In power down mode, the oscillator freezes and saves RAM data, stopping other functions of the chip until the external interrupt is activated or the hardware is reset.

The Q0-Q3 and DS1-DS4 outputs of the A/D converter are inputted into the microcontroller using a query method to input the thousands, hundreds, tens, and single digits, and these four digits are stored in RAM separately. The input data can be positive or negative, which can be determined based on the thousand bit Q2: when Q2=1, the data is positive; When Q2=0, the data is negative. By using software to determine whether Q2 is 1, the sign bit's polarity can be determined. Controlled by the microcontroller program, the symbol bit, thousand bit, hundred bit, ten bit, and single bit are sequentially output to the wireless communication chip through the microcontroller. In addition to the above functions, microcontrollers can also use software for calculation and data processing, calibrate nonlinear sensors, or automatically compensate for certain regular errors. This can fully utilize the functions of microcontrollers and improve measurement accuracy.

Industrial telemetry sensors

1. Use appropriate protective devices: Installing appropriate protective devices can effectively protect sensors from harmful factors such as mechanical shock, vibration, moisture, and high temperature, thereby ensuring their normal operation.

2. Regular calibration: After using the sensor for a period of time, due to factors such as environment, temperature, humidity, etc., the sensor may have certain errors. Regular calibration can avoid the accumulation of errors.

3. Avoid overuse: Although sensors can work for long periods of time, overuse can lead to sensor fatigue, and frequent use should be avoided.

4. Avoid strong magnetic field interference: Strong magnetic fields may affect the accuracy of sensors, and sensors should be avoided from working near strong magnetic fields as much as possible.

5. Adopt an appropriate working temperature range: Sensors usually can only operate within a certain working temperature range, and beyond this range, they will not function properly or be damaged. Therefore, the appropriate operating temperature range should be selected based on the technical specifications of the sensor and the actual situation.