Don’t know what type of controller you have? Here is a description of the 16 channel controllers.
 
1600 series Generation 1 or 2 – metal enclosure and no LED display inside.
1600 series Generation 3 –  metal enclosure with LED display inside.
CTB-16PC series Generation 1 or 2  – Typically in a plastic enclosure, red status light and has a jumper block to the right of the data cable connectors.
CTB-16PC series Generation 3 – Typically in a plastic enclosure, green status light and has a jumper block to the left of the data cable connectors.