SARA-R412M on Raspberry Pi

Before we test anything with the SARA module, we must first install Industrial Shield's librpiplc library by following the instructions in this link. We recommend you clone the repository inside of your home directory, as it is where we've cloned it for this blog. When cloning the repository, replace <tagname> with v3.0.0 to select the correct librpiplc version.

LIBRPIPLC Library

After succesfully installing librpiplc, we have to copy one of the compiled files into a different folder. If you installed a librpiplc version older than v3.0.0 you can skip this part. To copy the file, use the following commands:

(Replace [PLC_Version] and [PLC_Model] with your RPIPLC's version and model, like you did when installing librpiplc)

RPIPLC Models and Versions

cd ~/test/[PLC_Version]/[PLC_Model]/
cp set-digital-output ~/test/analog/set-digital-output

Now we must make sure that the config.txt file is set up correctly. To do this, first open /boot/config.txt with your preferred text editor, in this case we use nano:

sudo nano /boot/config.txt

Use your arrow keys to reach the bottom of the file, and make sure you have these lines set up like this:

[all]
dtparam=spi=on
gpio=8=pd
dtoverlay=spi0-1cs,cs0_pin=7
dtoverlay=w5500,cs=0,int_pin=6
dtparam=i2c_arm=on
dtoverlay=i2c-rtc,ds3231
dtoverlay=sc16is752-spi1-rpiplc-v4,xtal=14745600
enable_uart=1

You can now close the text editor. If you opened the file using nano, you can close it by pressing Ctrl+X. If nano asks you for confirmation before closing, type Y to confirm and then press Enter to keep the same filename.

Now we can work with the SARA-R412M module. Depending on where the module is installed, the following steps will be a bit different. The module can either be installed in slot 1 or slot 2, with slot 1 being the closest to the ethernet port.

wget https://apps.industrialshields.com/main/rpi/rpiplc_v4/setup-gprs.sh
chmod 755 setup-gprs.sh
sudo ./setup-gprs.sh

wget https://apps.industrialshields.com/main/rpi/rpiplc_v4/setup-gprs.sh

nano setup-gprs.sh

chmod 755 setup-gprs.sh
sudo ./setup-gprs.sh

If you followed the steps for your corresponding slot, the executed script will now be asking for APN credentials and AT (Radio Access Technology): LTE Cat M1(4G), NB-IoT (Narrow Band) or GPRS/eGPRS. It will also create a service called pppd located in /lib/systemd/system/pppd.service, which executes a python file created in /usr/src/network-setup.py every time the Raspberry PLC boots. 

About 50-120 seconds after executing setup-gprs.sh, interface ppp0 should be created. The process can be followed with:

tail -f /var/log/messages

or

tail -f /var/log/syslog

You can check that the interface has been created with:

ifconfig ppp0

To ensure everything has gone flawless, you can ping to 8.8.8.8 like so:

ping 8.8.8.8 -c4 -I ppp0

To stop and disable the service, use the commands:

sudo systemctl stop pppd.service
sudo systemctl disable pppd.service

Finally, try to execute the created script newtork-setup.py with the desired RAT:

(replace [RAT] with either gprs, nb-iot or lte-m)

    python /usr/src/network-setup.py [RAT]