liquid particle counter

We have just installed new liquid particle counter RION KE 28b and sensor ks 28b monitor has two channels counting particle but i am not sure which size it is counting. at the back portion of the ks28b particle size label is 0.5µm and 2.0µm. Are these parameters the basis of which channel it is going to read. Thus at channel 1 we have 0.5µm below and at channel 2 from 0.5µm up. But again i checked ks 28b the particle diameter classification is
0.2µm, and 0.5µm 2 stages for each particle diameter or more. Now i am so much confused. please help me....