4G/LTE Serial Server E840-DTU（4G-01）User Manual
Copyright ©2012–2017，Chengdu Ebyte Electronic Technology Co. LTD. 8
Before testing, connect the serial cable, SIM card, antenna and other hardware according to the recommended circuit.
1、 1. Enter the AT command mode and send +++ in the serial port assistant (except for +++ , one does not need to check to send a new line,
other AT commands need to check to send a new line to be valid), one must send any other AT command within 3s after sending +++
command (except for restarting the AT command) to enter the AT command mode completely.
2、 After entering AT command mode，use AT+CPIN to check SIM card connection status：
For example：AT+CPIN
+OK=1
Means SIM card is connected，use AT+CSQ to read current signal strength;
For example：AT+CSQ
+OK=26
Indicates that the current signal strength is normal. If the response is 99, the current signal strength is abnormal. Check whether the current
antenna is connected or whether the surrounding base station is abnormal.
Execute the parameter modification command. If the baud rate is modified, it needs to be restarted to be valid.
3、 Connect to server，AT+SOCK=TCPC,116.62.42.192,31687 （The parameters are separated by commas in English characters, and the IP
commands are separated by English characters.），for SOCK1，SOCK2，SOCK3，one needs to add an enable command on the front end.
SOCK setting
For example：AT+SOCK=TCPC,116.62.42.192,31687
+OK
SOCK1、SOCK2、SOCK3 setting
For example：AT+SOCK=0,TCPC,116.62.42.192,31687
+OK
Setting succeed。
4、Restart
After returning +OK, it is necessary to restart the command AT+REBT to be valid. Here, the IP is only used for demonstration. The actual
connection is based on the IP of the server to be connected.
