Your Epson Stylus NX110 Series and its software will let you know when an ink cartridge is low or expended.
If ink is low, the 
ink light flashes. You can continue printing until a cartridge needs replacement.
ink light flashes. You can continue printing until a cartridge needs replacement.If a cartridge is expended, the 
ink light stays on. You must replace the cartridge to be able to print.
ink light stays on. You must replace the cartridge to be able to print.
Note:
If you need to change a cartridge before it or any other cartridges are low or expended, run the Ink Cartridge Replacement utility.
You cannot print or copy when an ink cartridge is expended even if the other cartridges are not expended. Replace any expended cartridges before printing or copying.
Leave your old cartridges in the Epson Stylus NX110 Series until you are ready to replace them to prevent the print head nozzles from drying out.
If you need to change a cartridge before it or any other cartridges are low or expended, run the Ink Cartridge Replacement utility.
You cannot print or copy when an ink cartridge is expended even if the other cartridges are not expended. Replace any expended cartridges before printing or copying.
Leave your old cartridges in the Epson Stylus NX110 Series until you are ready to replace them to prevent the print head nozzles from drying out.
When an installed ink cartridge is more than six months old, you may need to replace it if your printouts do not look their best, even after cleaning and aligning the print head.