@keesjan With micropython, port 22 works fine, and as expected:
CDS_PIN = 33
TX = 19
RX = 22
As an aside, the idea that the labeling of the pins is "oriental logic" shows an unawareness of the history of rs232 and is a bit insulting. The question of what to label the pins depends on whether the manufacturer thinks of the device as DTE or DCE: StackExchange has a good explanation of the history.
'some manufacturers try to "help" by effectively labelling their DTE equipment as if it was a piece of DCE. They mark their data input pin as Tx so that user just connects "Tx" from the external device (which, if it's DTE, will be the data output from there) to the pin marked "Tx" on their equipment (which they know is an input). Thereby allowing them to say "just connect Tx on your device to Tx on our equipment". They think they are trying to help, but such labelling often just adds to the confusion.'