SainSmart Relay Control Library

The sainsmart_relay library provides an interface and command-line tools to control SainSmart relays via FTDI's bit-bang mode.

Installation

Linux Prerequisites

The FTDI USB drivers should be installed by default in most debian distributions. If not, try:

sudo apt install libftdi1-2

In order to access devices as non-root user we need to add the local user to the dialout group and add a udev rule:

sudo usermod -a -G dialout $USER

# logout / reboot

# Add udev rule:
sudo touch /etc/udev/rules.d/99-libftdi.rules
# Add this line:
# SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", GROUP="dialout", MODE="0660"

Python Library

To install the library, ensure 3.8 <= Python <= 3.11.

First, clone the repository:

git clone https://github.com/yourusername/sainsmart-relay.git
cd sainsmart-relay

Then install the library:

pip install .

Usage

Relay Server

To start the relay server, run:

relay-server

This will start the server that listens for commands to control the relays.

Relay Client

To control the relays or query their status, use the relay command.

Change the state of a relay:

relay 1 on  # Turns relay 1 on
relay 2 off # Turns relay 2 off

Get the current status of all relays:

relay -s  # Displays the status of all relays

Python API

The sainsmart_relay can also be used as a module in Python scripts:

from sainsmart_relay.relay import FTDIBitbangRelay

# Initialize the relay controller with the device ID
relay_controller = FTDIBitbangRelay(device_id='your_device_id')

# Turn relay 1 on
relay_controller.set_relay(1, 'on')

# Retrieve the current relay state
state = relay_controller.get_relay_state()
print(f"Current Relay State: {state:08b}")

Replace 'your_device_id' with the actual device ID of your FTDI device.