Sometimes, when controlling lights and other loads such as motors, pumps, Solenoids etc., problems occur. Problems may include:

Lockup of the Arduino controlling the relays and switching
Loss of ability to communicate with a PC connected to the Arduino by USB
Noise and erroneous readings on sensors or attached devices when relays or loads are switched

24V Industrial I/O Shield PLC Replacement
79.95
Update old, dated, and clunky PLCs with a modern Arduino/Pi based system. The Rugged Circuits 24V Industrial I/O Shield is designed to replace costlier PLC systems.

With little effort, anyone can assemble sensors and other electronic components, integrate them on an Arduino board and use it with any MOD device. Copy and paste some lines of code, solder components on the breadboard and easily design your controller of MOD effects.