Relay output type
Relay output type relays can connect to AC loads or DC loads, and are polarity-insensitive. Internally, they use dry contacts, requiring an external power supply for the load to operate. Compared to transistor relays, relay output type relays can handle slightly higher power loads. However, their response frequency is slightly slower, and their contacts have a limited mechanical lifespan.
Transistor output type
Transistor output PLCs require strict polarity connection at the output terminals. Otherwise, they will not function. When selecting a PLC, pay attention to the polarity of the common terminal to ensure compatibility with the load. Transistor output PLCs are slightly weaker in terms of load power but have a high response frequency. They can only connect to DC loads, not AC loads. Their output terminals include high-speed pulse signal terminals, allowing connection to servo stepper devices.
Thyristor output type
Thyristor-type output PLCs overcome the shortcomings of relay-type output PLCs. They can connect to AC loads and respond quickly. However, they can only connect to AC power and drive AC loads. Thyristor-type output PLCs are not widely used. The first two types are the mainstream.
