Unfortunately it has nothing to do with physical connection.
As many posts pointed out, TS-570D relied on hardware RTS/CTS flow control, which digirig does not supported(the RTS is being used as PTT control). It might also need the DTR PIN on high.
As a result, I have to buy a dedicated RS232 adapter along with RS232 gender converter(NOT null-modem) to get the CAT control to work.
Now I’m having a different problem. The audio level is too low, which I’m going to discuss in a separate thread