Solution:

ADAM-4521 is addressable RS-485 to RS-232 converter, if you would like to add certain RS-232 device on RS-485 network, ADAM-4521 can help you to do that and give an unique ID to this RS-232 device so that you can find it under RS-485 network. Actually, ADAM-4521 supports 2 modes as follows: A. Addressable mode: You can assign an ID and select one of 8 delimiters for RS-232 device so that you can communicate with RS-232 device through RS-485 network. Besides, ADAM-4521 can allow different baudrates between RS-232 and RS-485, you can adjust baudrate and protocol for RS-232 side under ADAM-4521 utility to fit your RS-232 device, but you only can change baudrate of RS-485 side. B. Non-addressable mode: You can change mode to non-addressable under utility, after that, the function of ADAM-4521 is similar to ADAM-4520's. You can regard ADAM-4521 as a converter just like ADAM-4520, however, you need to set baudrate under utility to fit your Host PC, just like DIP switch for ADAM-4520, but RS-232's protocol (Parity, Data bit and Stop bit) is fixed, you can't change it, you must switch mode to addressable first then it is allowed to modify it. Actually, there is a microprocessor built-in ADAM-4521 to handle transmitting/receiving, that's why ADAM-4521 can use different baud rate between RS-232 and RS-485. Because of this microprocessor, there is a little delay compare to ADAM-4520 while converting signals, but it should not effect converting function.