What is the difference between a transistor output and a relay output?
Although both are control devices, but the transistor input and output are not galvanically isolated, and the relay is electrically isolated, when the volume is limited, the response time is very short, are often used to control the transistor, and the voltage is relatively high , The current is relatively large, pay attention to personal safety, often with the relay ...
Transistor is mainly used for positioning control, the use of crystal output to send pulses. And the relay can not use the pulse, it can not be positioned control. If you use the relay to control the positioning of the servo or step, then also need to add positioning module, the economy is not worth. And with a transistor output can control the servo and so on.
PLC transistor output response fast, can be used for high-speed output, but the control solenoid valve or the need to add intermediate relay; relay output response is slow, but can save an external relay, wiring is simple. What specific output depends on the load depending on the circumstances.
