Scenario

In automation systems, digital outputs are commonly either contact (relay) outputs or transistor outputs. Both are used to switch signals ON and OFF, but they operate in different ways.

 

 

Feature	Contact Output (Relay Output)	Transistor Output
Operation Type	Mechanical switch with moving parts	Electronic switching (no moving parts)
How it Works	Metal contact physically opens/closes	Electronic component controls current flow
When ON	Contact closes, current flows	Allows current to flow
When OFF	Contact opens, current stops	Blocks current flow
Voltage/Current Capacity	Supports wider voltage range and higher current	Supports lower voltage and current range
Speed	Slower due to mechanical movement	Faster switching
Durability	Wears over time (mechanical parts)	Longer lifespan (no mechanical wear)