Generally believed to work does not require an external power supply signal isolation, passive isolator; and active isolators will need a dedicated external power supply, such as 24VDC or 220VAC.
Passive isolator advantages:
1. Easy to use, highlighting the economy, after all, save for the isolator power supply and power cord;
2. Low power consumption and high reliability. Passive isolators low power consumption, such as stable titanium grams TA2000 series passive isolator consumes only 0.07W / channel (20mA output typ), compared with the same active role isolator to an order of magnitude, lower power consumption that the lower heat, thus ensuring the reliability of the isolator.
Active isolator advantages:
1. equivalent input impedance lower output terminal with capacity to carry more;
2. The input signal may be a current signal may be a voltage signal or a signal other, more powerful.