USR-DR504-E User Manual
Jinan USR IOT Technology Limited
Tech Support: h.usriot.com
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3.1.2. AT command setting
When the device works in either the network transparent mode, the device can switch to the "AT command
mode" by sending time-specific data to the serial port of the device.
When the operation is completed in "AT command mode", the device is sent specific commands to return to the
previous working mode.
Diagram 3.1.2-1 Time Line
Changing the timing of command mode:
In the figure above, the horizontal axis is the time axis, the data above the time axis is sent by the serial port device to
the device, and the data below the time axis is sent by the device to the serial port.
Time requirement:
T1> current serial port packaging interval (refer to AT+UARTFT)
T2 < current serial port packaging interval time (refer to AT+UARTFT)
T3 < current serial port packaging interval time (refer to AT+UARTFT)
T4 = current serial port packaging interval time (refer to AT+UARTFT)
T5 < 3 s
T6 = current serial port packaging interval time (refer to AT+UARTFT)
The time sequence of switching from Transparent transmission mode to AT Command mode:
Serial port device continuously sends "+++" to the device. After receiving "+++", the device will send an "a" to
the serial device. No data can be sent during a packaging cycle before sending "+++".
When the serial device receives 'a', a 'a' must be sent to the device within 3 seconds.
After receiving 'a', the device returns "+ok" and enter “temporary command mode”.
After receiving "+ok", the device has enter "temporary command mode" and now can send AT command to it
Time sequence of switching from AT command mode to network Transparent transmission mode”
The serial device sends "AT+ENTM" to the device.
After receiving the command, the device sends "OK" to the serial device and returns to the previous working
mode.
After the serial device receives "OK", it knows that the device has returned to its previous working mode.