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RockBLOCK 9704 Python Walkthrough

Introduction​

The RockBLOCK 9704 is the most convenient and cost-effective way to add satellite IoT communication (via IMT) to your project. It offers efficient power management, flexible serial I/O options, and access to our development SDKs and Cloudloop Data service for true ‘plug and play’ satellite connectivity.

This Getting Started guide provides a crash course in using the RockBLOCK 9704 with a commonly available, Python-capable microcontroller platform. The example setup uses a USB serial interface and our open-source Python library available on PyPi to send and receive messages via the Iridium satellite network — giving you a foundational understanding to build your own satellite-enabled solution.

This guide is intended as an illustrative walkthrough.

For full documentation and more advanced code examples, please refer to:

• Python Library (rockblock9704): https://pypi.org/project/rockblock9704

• C/Arduino SDK and hardware reference: https://github.com/rock7/RockBLOCK-9704

What You’ll Need​

To complete this guide, you’ll need:

  • RockBLOCK 9704 (either SMA + Antenna or Patch variant)
  • A valid Iridium airtime & data plan (you’ll have the option to purchase this during setup)
  • A device capable of running Python scripts, with USB support (e.g. a Raspberry Pi Zero, USB-equipped microcontroller, or single-board computer)
  • MicroSD card + power supply (for your chosen device, if required)
  • USB-C cable to connect the RockBLOCK 9704 (e.g. USB-C to Micro-USB if using a Pi Zero)
USB Cables

Ensure your USB-C cable supports data as well as power — not all USB cables are data-capable.

Hardware Setup​

Step 1: Activate your RockBLOCK 9704​

warning

Skip this step if you already have a Cloudloop account

Unbox your RockBLOCK 9704 and locate the serial number printed on the Iridium modem. You’ll now need to create a Cloudloop account and register your device:

👉 https://join.cloudloop.com

Once your account is set up, follow the prompts to add your RockBLOCK 9704, select a data package, and activate airtime.

Step 2: Prepare your Device​

In this example, we’re using a Raspberry Pi Zero — a low-cost, compact Linux computer ideal for prototyping satellite IoT applications. You can follow similar steps with any device that supports Python and has USB host capabilities.

If using a Raspberry Pi Zero:

  1. Download the Raspberry Pi Imager: 👉 https://www.raspberrypi.com/software
  2. Use the Imager to install a suitable OS — we recommend Raspberry Pi OS Lite (64-bit) for this guide.
  3. Optionally, enable SSH and configure Wi-Fi during the image creation process so you can access your device headlessly (without monitor or keyboard).

Development Environment Setup​

We will be using Python to control the sending and receiving of messages, and the core package is included in the Raspberry Pi OS so we will just need to install the RockBLOCK 9704 library.

Step 1: Create a Virtual Environment​

Firstly we will create a virtual environment to both install the required libraries and from which we will run our Python scripts:

python3 -m venv --system-site-packages rb-env

Step 2: Activate the Virtual Environment​

source rb-env/bin/activate

Your cursor should now be prefixed with your virtual environment name (rb-env)

Step 3: Install the RockBLOCK 9704 Python Library​

pip install rockblock9704

Connect your Pi Zero and RockBLOCK 9704​

Use a USB-C to Micro USB cable to connect your devices together.

9704piZero.png

With both devices powered on and connected, we can use our python library to validate the connection and report some device statistics.

Step 1: Identify the RB9704 connection​

With the RB9704 connected via the USB cable, we need to identify what name has been allocated to the connection and note this down for use in our script:

ls /dev/tty*

or

dmesg | grep tty

The name can vary from machine to machine, but will typically be something like ttyUSB0 or tty.usbserial-XXXXXXXX

note

The RockBLOCK 9704 will appear as a USB serial device — no additional drivers required on Linux-based systems.

Step 2: Create a Python test script​

Now we’ll create a short test script to validate the connection and ensure we can read some details from the device. Firstly, create the test script:

nano testRB9704.py

Then add the following code which will create a connection to the RockBLOCK 9704 (using the tty* name you identified) and display connection status:

from rockblock9704 import RockBlock9704

rb = RockBlock9704()
connected = rb.begin("/dev/ttyUSB0")

if connected:
    print("Successful connection!")

serial_number = rb.get_serial_number()
print("Serial number: {}".format(serial_number))

card_present = rb.get_card_present()
sim_connected = rb.get_sim_connected()
if card_present and sim_connected:
    print("Sim card valid")

If everything is connected properly you should see a successful connection, the serial number you noted previously, and that the Sim card is valid.

Sending Messages from your RockBLOCK 9704​

With everything successfully connected, we can now get to the exciting part of sending and receiving messages via satellite.

Step 1: Check you have a good satellite signal​

Fun fact, the Iridium satellites are orbiting the earth at 30,000 km per hour! To ensure our message is able to reach one of these, then your antenna must have a clear view of the sky, free from any obstructions such as tall buildings, trees, and hilly or mountainous terrain. We’ve provided a handy guide on how to check this in more detail.

Step 1a (optional): Check you have a good satellite signal​

The following simple Python code will poll your RockBLOCK device to check for signal strength, which can be handy when trialling a new location. Signal strength ranges from 0 (no signal) to 5:

Checking Signal Strength

Please note that it is not necessary to check signal connection prior to sending or receiving messages - this is to enable you to find and verify a good location.

import time
from datetime import datetime
from rockblock9704 import RockBlock9704

print("Polling for Signal - Press CTRL+C key to stop...")
# Initialize globally
rb = RockBlock9704()
iteration = 1

if not rb.begin('/dev/ttyUSB0'):
	print("Failed to connect to RockBLOCK.")

while 1:
    timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S");
    signal_strength = rb.get_signal();
    message = f"Signal Strength = {signal_strength} Iteration {iteration} | Last run: {timestamp}"
    print(message.ljust(60), end="\r", flush=True)  # ljust pads to clear remnants
    iteration += 1
    time.sleep(5)

Step 2: Send a message​

Great, now you’ve located your RB9704 with a good signal to the satellite then it’s time to send a ‘Hello World’ message:

from rockblock9704 import RockBlock9704

# Always check if begin has returned successfully
rb = RockBlock9704()
connected = rb.begin('/dev/ttyUSB0')

if connected:
print("Successful connection!")

    # Sending message
    sent = rb.send_message(b"Hello, world!", timeout=60)

    if sent:
        print("Message sent!")
    else:
        # If the timeout expires
        print("Sending failed")

Receiving Messages to your RockBLOCK 9704​

Step 1: Checking for received messages​

The Iridium 9704 modem does not support onboard message caching and therefore it is imperative that you are checking for messages on your device regularly to ensure they are not missed. The following simple code will poll for, and display, messages every 1 second and you can set this running before sending a message to the device and monitor the signal and message receipt.

if your project requires sophisticated onboard management of message queuing and retries then take a look at our RockBLOCK Pro and RockREMOTE range.

import time
import sys
from datetime import datetime
from rockblock9704 import RockBlock9704

def main():
    rb = RockBlock9704()
    # Always check if begin has returned successfully
    if not rb.begin('/dev/ttyUSB0'):
        print("Failed to connect to RockBLOCK.")
        return;
    last_connected_time = "N/A"
    iteration = 1
    # Check for a message
    print("Polling for Messages - Press CTRL+C key to stop...")
    while  1:
        timestamp = datetime.now().strftime("%Y-%m-%d %H:%M:%S");
        signal_strength = rb.get_signal(); 
        if signal_strength > 0:
            last_connected_time = timestamp
            inbound_message = rb.receive_message()
        status_message = f"Signal Strength = {signal_strength} (last connected at {last_connected_time}) Iteration {iteration} | Last run: {timestamp}"
        sys.stdout.write('\033[2K\r')
        print(status_message, end="", flush=True)
        iteration += 1
        if inbound_message is not None:
            print("Message Received!")
            print(inbound_message)
        time.sleep(1)
    
if __name__ == "__main__":
    main()

Step 2: Sending a test message to your RockBLOCK 9704​

The simplest way to send a message to your RockBLOCK 9704 is to utilise our Cloudloop platform: https://data.cloudloop.com/

Login with the account you created earlier and locate your device in the ‘Things’ collection. Once you have clicked on your device you should see the option to ‘Send Message’.

Choose IMT as the message type and add your text to the ‘Payload’ section and hit ‘Send’.

Your message will now be sent to your RockBLOCK 9704 over the Iridium network, and should appear within a few seconds depending on signal availability.

Prefer Automation?

You can also send messages programmatically via the Cloudloop API — ideal for integrating with your own platform or server-based tools.

What Next?​

🎉 Congratulations, you’ve completed setting up your device and can successfully send and receive messages!

For a more expansive overview of our RockBLOCK 9704 SDK, then review our online documentation: https://docs.groundcontrol.com/iot/rockblock-9704/intro

If you would like to connect to the RockBLOCK 9704 via the serial (UART) interface, power via a battery, or enable GNSS passthrough; then review our hardware specification for pinouts and power requirements: https://docs.groundcontrol.com/iot/rockblock-9704/hardware

To get started with writing your own RockBLOCK 9704 application, please review our Readme

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