Discussion Overview
The discussion revolves around creating a hardware setup to monitor the Bit Error Rate (BER) of a Modbus communication system, specifically between a PC (master) and a compressor (slave) using the Modbus RTU protocol over an RS485 line. Participants explore methods to quantify communication errors and propose various approaches to achieve this monitoring.
Discussion Character
- Technical explanation
- Experimental/applied
- Debate/contested
Main Points Raised
- One participant describes the need to measure BER in a Modbus communication setup and mentions coupling white noise and burst signals to the line.
- Another participant suggests that if the transmitted and received data are known, a bit-by-bit comparison can be made to determine errors, assuming no error correction is in place.
- There is a question about whether the Modbus RTU protocol includes a checksum or CRC, and the length of that checksum or CRC.
- A participant confirms that the Modbus signal includes a CRC and inquires about the number of bits in the CRC.
- Another participant proposes that if each packet has a CRC check, the packet error rate can be calculated and multiplied by the average packet length to estimate BER.
- It is suggested that the testing should involve sending numbered packets to identify any packet loss that does not result in a CRC error being logged.
Areas of Agreement / Disagreement
Participants express various methods for measuring BER, but there is no consensus on the best approach or the specifics of implementation. Some participants agree on the importance of knowing the transmitted and received data, while others raise questions about the CRC and its implications for error measurement.
Contextual Notes
There are unresolved questions regarding the specifics of the CRC implementation and how it affects the measurement of BER. Additionally, the discussion includes assumptions about the absence of error correction and the need for precise definitions of packet structure.
Who May Find This Useful
Individuals interested in Modbus communication, error measurement in digital communication systems, and those working on hardware setups for monitoring communication performance may find this discussion relevant.
