plc cpu modules connected to 4G steps

1 When using the terminal, why type "AT + CFUN = 1", returned ERROR?
A: In the instructions to enter the correct premise, first confirm whether the 4G module with pc connection is successful, check plc cpu modules Device Manager - Universal Serial Bus Controller is connected to  plc cpu module the device, if the device exists, then make sure USB line with the PC connection is successful, and then determine whether the module is turned on, press power button for 5 seconds, and power module, when returning + CEREG: 1:00, enter "? AT + COPS", registered network. 2 How to check the current registered network provider?
Answer: Enter "? AT + COPS", according to the return value to determine the current registered network provider. Returns + COPS: 0,0, is not registered to the network + COPS: 0,0, "CHINA MOBILE", 0 indicates registration to China Mobile's 2G network; + COPS: 0,0, "CHINA MOBILE", 2 means that the registration to China Mobile's 3G network + COPS: 0,0, "CHINA MOBILE", 7 indicates registration to China Mobile 4G network; 3 Why type, return ERROR. "AT + COPS?"?
A: In the instructions to enter the correct premise, the SIM card may be the problem, first check whether there is a SIM card slot confirm balances, confirm the SIM card and the antenna is plugged in, then enter "AT ^ DUSIMR" SIM card status query returns ^ DUSIMR: 1 indicates the plc input output modules  presence of a SIM card; enter "AT + CLCK =" SC ", 2" check SIM card LOCK state, return "+ CLCK: 0 \ r \ n", the SIM card is not LOCK; enter "AT + CPIN? "check whether you need to enter the PIN code, return" + CPIN: READY "said PIN has been entered, and do not need to enter a PIN code;
 4 How to activate data services?
A: Enter the "AT + CGDATA =" M-0000 ", 1" when returning CONNECT, surface data service activation is successful, then you can find the network connection is successful;
 5 Enter the AT commands connect to the  cpu modules plc Internet course, if there is a power outage, you can continue to operate in serial tool it?
A: No, plc cpu modules serial communication tool again to close the operation;
 6 Enter the AT commands connect to the Internet course, if there is usb interface is bad, you can continue to operate in serial tool it?
A: No, you need to re-open the serial port and enter "AT + CFUN = 4" soft shutdown, then enter "AT + CFUN = 1" to get started. 7 Why 4G network connection (to activate data services) yellow exclamation mark appears, the network connection status is displayed without Internet access?
A: In the case of an unstable 4G network, the network may jump to 3G or 2G network, but the SIM card only supports 4G networks,
Enter the activation of data services in the command (AT + CGDATA = "M-0000", 1) before, enter "AT ^ DSTMEX = 1,7", this command indicates that only select Connect 4G network, and then enter "AT + CGDATA =" M-0000 ", 1" to activate data services, conduct 4G network connection.