The 1784-PCD1 and 1784-PCIC modules are both part of the Rockwell Automation product line, specifically the Allen-Bradley brand. These modules are used in programmable logic controllers (PLCs) for industrial automation applications. 

The 1784-PCD1 module is a DeviceNet scanner module designed for communication between a PLC and DeviceNet devices. It provides the interface for the PLC to communicate with and control devices connected on a DeviceNet network.

The 1784-PCIC module, on the other hand, is an interface card used for connecting a computer to a PLC controller. It allows the computer to communicate with the PLC and exchange data for programming, monitoring, and controlling the automation system.