Frequently Asked Question
The QG40N SIL1 tilt switches play a vital role as critical safety switches, meticulously crafted with a variety of designs to guarantee the reliable functionality across diverse applications. Comprehensive safety checks are performed during both the startup and operational phases. In case of any diagnostic errors, both sensor outputs are forcefully switched to a "non-conducting" state in a permanent manner to inform the application that an unsafe situation could occur. Want to learn more about how tilt switch work? Please read "How does a tilt switch work?"
Below is a list of several essential safety checks for a SIL1 tilt switch:
- MCU EEPROM error
- MEMS Self-test error.
- Output error.
- MCU errors.
MCU EEPROM error check involves verifying the integrity of the EEPROM data. The microcontroller's firmware calculates a checksum or uses a cyclic redundancy check (CRC) algorithm on the stored data. This computed value is then compared with a pre-determined reference value. If they match, it indicates that the EEPROM data is valid; if not, an error is detected. This process ensures that data stored in the EEPROM remains accurate and uncorrupted.
The MCU briefly activates the MEMS acceleration chip's self-test mode to verify its proper functionality.
As a component of the required Diagnostic Coverage for achieving SIL1 functional safety, it is necessary to monitor the switching output of the sensor. To facilitate this, the SIL1 tilt switch incorporates a feedback mechanism from its output to the microcontroller. If the logical feedback deviates from expected parameters, the sensor transitions into a permanent critical state until a system reboot is performed. It is crucial to ensure the correct operation of the sensor that no voltage is applied to the NPN or PNP outputs.
The MCU is a key component that manages the sensor's operation, data processing, communication, and other functions. Therefore we continuously monitor error or fault that occurs within the MCU.
- Unknown interrupt
An MCU might not handle interrupts correctly, leading to missed sensor events or incorrect responses to interrupts.
- RAM error
- FLASH error
- Watch Dog error
The MEMS use the interrupt line to indicate the availability of the output. By implementing robust error-handling mechanisms in the firmware, we can detect and handle interrupt errors. Log error information for debugging purposes.
A "Sensor Data Format Error" refers to a situation where the format of the data obtained from MEMS does not match the expected or specified format.
Voltage errors can occur due to various reasons, such as power supply fluctuations, noise, or issues with the sensor itself. Checking for voltage errors is crucial to ensure that the voltage supplied to the sensor falls within acceptable limits for proper and safe operation.