The IQ251 is a large capacity controller, it can provide up to 128 I/O points by connecting 8 I/O modules in any combination. The range of I/O modules comprises 4 x 8 analogue plus 8 digital input modules, 3 x 8 analogue output modules, and 1 x 8 digital output modules. This IQ251 Controller comes with 8 modules, the photograph is just an example of what the controller looks like with 8 modules.