For additional digital inputs and outputs there are a number of plug-in options available that can supply extra input and output connection points to the drive. OPT-2-EXTIO provides three extra digital inputs and one relay output OPT-2-CASCD offers three relay outputs, suitable for applications such as a cascade control of several pumps OPT-2-ENCOD is a plug-in feedback interface for Optidrive P2, allowing closed loop motor control. The interface is compatible only with 5V TTL type encoders, up to 4096 ppr.