For MYTHEN, if one needs to control 6 modules, the system can either be composed by and MCS6 with 6 modules (1 detector, 1 controller, 6 modules), or by 6 MCS1 (1 detector, 6 controller, 1 module each). After apppropriate configuration of the system, the interface to the user will be the same for both systems.
For GOTTHARD, one module corresponds to one controller. A detector will have the smae number of controllers and modules.
For EIGER, one module consists in two controllers. Fo a multi-module system, the number of controllers will increase accordingly, but should be left to a configuration file.
You will need to configure more than one detector, only in case you want to operate several detectors independently.