A module card adds functions to the MI. For example, a relay module card contains 2 relays that can be used as wash relays or alarm relays. There are 8 module card slots inside an MI. Each MI is shipped with one relay module card with 2 independent relays and one mA output module card with 2 independent 4 … 20 mA outputs as a standard. These are already installed in the MI. In addition to the relay module card and the mA output module card, there is a general input/output module card with 8 digital inputs/outputs. These module cards have the capability to be used in any combination as well as added and removed as needed.