download to plc ac800m
1) Check IP address of controller, e.g. with serial cable connected to port #4 - use HyperTerminal (XP) or PuTTY (3rd party commonly available) to listen to what the controller output when it boots. IP address is shown after some delay when reset.
2) Check IP address of your PC
Computer and PLC must share same subnet for ping to work.
Change of controller address require reset before taking effect.
If you reset the controller to the factory reset and if the IP address set in the PC from where you are accessing the factory resetted controller if not in the same subnet mask you can't access.
So to access the controller first set the IP address in the controller to the desired IP as per your requirement with subnet using Tk212 cable to Com4 of AC800M.