A new Slot for a slave device is created with the module parameter values and signals specified for that Device Definition in the Library. These values can be overwritten at the Slot level but new instances of the device or module will not inherit this value. Slots can be added until the maximum number of bytes and slots specified by the device manufacturer for that device have been met. When you add a new Slot, the dialog displays the manufacturer's limits and shows you the number of used and available bytes and slots. There is a maximum limit of 255 signals that can be configured for any one Profibus slot configuration.
The .GSD file specifies the number for the first slot. The default is 0. You must number the Slots contiguously to successfully download the device. The Profibus protocol specifies that there can be no gaps in Slot numbers. The Slot types and Slot order of the physical device must match the configuration in the DeltaV configuration database or the device can not establish communication with the master.