LTE stick CU8210-D004-0200 under Beckhoff RT Linux

This chapter describes the commissioning of the LTE stick CU8210-D004-0200 under Beckhoff RT Linux. The stick enables a mobile data connection via the mobile network.

Requirements

LTE stick CU8210-D004-0200
Valid and activated SIM card
Access to the shell of the Beckhoff IPC (locally or via SSH)

Insert the LTE stick with the SIM card inserted into a USB port on the IPC. After a short time, the device is recognized by the operating system and a serial interface is created.

Determine serial device interface

1. First determine the newly created device interface.

ls /dev

2. Search for an interface of type ttyACM* in the output. Example:ttyACM0

3. Make a note of the device name (e.g. /dev/ttyACM0), as this is required for further configuration.

Configuring access to the serial interface

A corresponding udev rule must be created so that users can access the serial interface.

4. Create a new rule file:

sudo nano /etc/udev/rules.d/99-usb-serial-acm.rules

5. Insert the following content:

SUBSYSTEM=="tty", KERNEL=="ttyACM0", MODE="0666"

6. Save the file and then reload the udev rules:

sudo udevadm control –reload
sudo udevadm trigger --attr-match=subsystem=tty

7. Alternatively, you can restart the device:

sudo reboot

Install serial terminal program

A serial terminal program is required for communication with the LTE stick.

8. First check whether the program cu is already installed:

which cu
cu –version

9. If the program is not available, install it:

sudo apt-get install cu

Establishing a connection to the LTE stick

10. Then use the cu program to connect to the previously determined serial interface.

sudo cu -l /dev/ttyACM0

11. If the connection is successful, appears in the terminal: Connected

12. Test the communication with the modem by entering the following command:

at

13. Confirm with Enter. If communication is successful, the modem responds with : OK

Configure modem (PIN and APN)

So-called AT commands can be sent to the modem via the serial connection. These are used, among other things, to:

enter the SIM PIN
deactivate the PIN
configure the APN (Access Point Name) of the mobile phone provider

An overview of the relevant AT commands can be found in chapter 5.4 of the device manual.

Terminate connection

Exit the cu program with the following shortcut:

Direct terminal connection:

~.

then Enter

For SSH connection:

~~.

then Enter

Check network connection

Once the PIN and APN have been configured correctly, the modem automatically connects to an available mobile network.

Check the network interfaces with :

ip address

An additional network interface should appear in the output (e.g. enx…). If the connection has been successfully established, this interface has an IP address.

Test the Internet connection with a ping, for example:

ping 8.8.8.8