Notes - Ebyte E840-DTU User Manual

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4 .Notes

The first Socket of this module will always be opened. After the initialization is successful, it will automatically
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establish a connection with the configured network server.
After the module is powered on, it cannot be initialized successfully. That is, the State indicator has no indication
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for more than 30 seconds. In this case, check whether the module is installed properly, whether the SIM card is
properly inserted, and whether the SIM has failed.
Short connection function can be used to reduce the connection pressure of multiple devices to the server. When the
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short connection function is enabled (AT+SHORTM>2), the module will actively disconnect the connection when
the network or serial port has no data for more than the short connection setting period. After the disconnection, the
network cannot send data and the local serial port sends. For valid data, the module will immediately establish a
connection with the server. If the local clear cache function is turned off, the packet will be cached (maximum 10K
bytes). After the connection is successful, the data will be sent to the server. The local cache function is cleared and
the packet will be discarded.
The heartbeat function is used to maintain the connection after the module and the server are successfully connected.
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In the network, if the client and the network server successfully establish a connection and there is no data
transmission for a long time, the Socket link may appear "dead", that is, the chain. The road exists but cannot send
and receive data. Therefore, in actual use, it is recommended to enable the heartbeat packet function to ensure the
reliability of the network link.
In actual use, it is normal for the data delay of the two communications to be different.
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After the protocol is closed, the maximum single packet length supported by a single link is 10K bytes. A local
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serial port or a network sending a packet exceeding this length may cause packet abnormality. The distribution
protocol is enabled. Each Socket is enabled. The link single packet can support up to 1024 bytes (user-configured
serial port packing length).
In the high-speed serial transmission mode, the EMBMAC and EMBCSTM registration package functions cannot
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be enabled, and in the high-speed mode, the short message transmission and reception function is not supported.
Only the first Socket effective link is valid, and the protocol distribution data is not supported.
After the EBYTE cloud transparent transmission function is enabled, the high-speed mode is invalid.
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When the device serial port outputs the words "pdp error, device will be reset!", it indicates that the PDP context is
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disabled by the network. The SIM card may be loose or the current network channel is occupied abnormally.
The SMS function needs to insert the SIM card to support the SMS service. The IoT card cannot send and receive
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SMS messages. When the device sends a text message, the device responds with OK only to indicate that the
module has sent the SMS, which does not mean that the device has received the SMS.
After modifying the serial port break time, the AT command must be configured according to the frame break time.
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For example, after setting the parameter to 2000ms, you need to configure the device parameters after power-on.
You need to send '+++'. , Send a valid AT command within the period of more than 2000ms and less than 3000ms
to enter the AT mode normally
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E840-DTU(4G-02E) User Manual
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