ADAM-4520/4521 modules don't need to control data in RS-485 mode, the modules will control the data flow direction automatically. You don't need any special software, simply treat it as a transparent RS-232 port.
ADAM-4521 is an addressable converter, i.e. it will be enabled only when it is addressed. The address and mode of ADAM-4521 can be configured by software commands. For RS-232 device not addressable, ADAM-4521 can be used as the interface.
Host PC send commands to the specific ADAM-4521 according to the address, ADAM-4521 then remove the address message and send the rest of data to the RS-232 device connected to it. ADAM-4521 also can be "opened" to work as ADAM-4520, i.e. it can work both at addressable mode or none-addressable mode.
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