Troubleshooting

No response or garbage data

• Confirm 19200 8N1 unless you have intentionally reprogrammed the sensor with #BAUD.
• Verify TX/RX are not swapped and grounds are common.
• Respect 3.3 V max on the FDO2 UART pins.
• Wait ≥ 1 s after power-up before the first command.

Timeout or ProtocolError

• Increase SetMeasureTimeoutMs (default 300 ms; #MRAW can be longer at high #SETM modes on device).
• Ensure no other task is reading the same UART concurrently without mutual exclusion.
• If CRC is enabled on the device, verify you are on a driver revision that strips the : <CRC> suffix (current main does).

DeviceError after #ERRO

Call LastDeviceErrorCode() and map E using Table 1 in the data sheet §4.4 (for example -22 UART receive, -26 unknown header).

Status S not 0 or 1

The data sheet requires checking S every sample. If MoxyStatusOkForOxygen returns false, treat pO₂ / temperature as invalid for safety-critical use until the fault clears (see bit definitions in fdo2::moxy_status).

Need more help?

Open an issue with UART capture, firmware R from #VERS, and software revision.

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