hi guys. i am interested in learning plc programming, so i acquired an old siemens logo! 230rl with its software (logosoft). i was told that i could program it through the keypad, but i cant. it just says "no program" in the plc's display. someone then told me the internal battery was flat, so i could only program it through a cable. i contacted siemens south africa, and they told me the plc was discontinued, so they could not help me with a cable. i don't have the money to buy a new plc just to learn on, so could anyone help me with schematics to build an interface? i do have electronics experience, but i am not familiar with the chips used in the plc, so i don't even know which interface will work. any help will be appreciated.