Can anyone help!

1)I want to automaticaly save a live excel workbook,
2)using the date and time as the save address
3)The iput to save the file will come from a plc input into the excel file i.e. i will put a 1 in cell A1
4)when their is a 1 in A1 i want vba to Auto save the file,
5)I will remove the 1 using plc control which iunderstand alot more than VBA

your help is appreciated!