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E91-DTU(xxxSL30) Frequently Asked Questions and Solutions

Users often encounter the following issues when deploying the Ebyte E91-DTU(xxxSL30) series LoRa radios. This article addresses them one by one.

Q1: The communication distance falls short of the rated 8 km. What should I do?

A: The 8 km rating is measured in open, unobstructed areas. In practice, the following factors can reduce range:

Obstacles such as buildings or trees in the line of sight
Metal objects near the antenna or the antenna enclosed in a metal housing
Supply voltage lower than the recommended value (12 V or 24 V is recommended)
Excessively high air data rate (higher rates reduce sensitivity and distance; use 2.4 kbps for maximum range)
Poor antenna quality or impedance mismatch (use Ebyte's recommended antennas)
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Q2: The module is prone to damage. How can I protect it?

A: Although the E91-DTU(xxxSL30) has built-in reverse polarity and overcurrent protection, please note:

Do not exceed 28 V DC on the power input
Ensure the power supply is stable with no large fluctuations
Follow anti-static precautions during installation and use
Never transmit without an antenna connected to avoid damaging the power amplifier
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Q3: How do I troubleshoot high bit error rates?

A: Common causes and solutions:

Co-channel interference: Change the channel (AT+CHANNEL) to avoid interference
Poor power quality: High ripple can cause data corruption; use a stable power adapter
Poor-quality or overly long antenna feeder cables: Use high-quality cables, ideally under 3 meters
Enable LBT (AT+LBT=1) to have the module listen before transmitting
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Q4: RS485 communication is abnormal. What should I do?

A: The manual specifically notes that when connecting multiple RS485 devices, if communication issues occur, connect a 120 Ω resistor in parallel between RS485-A and RS485-B to eliminate signal reflections.

Q5: How do I restore factory settings?

A: In configuration mode, send AT+DEFAULT. The module will restore factory parameters and automatically restart. Wait approximately 30 ms before proceeding.

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