The Allen Bradley 1756-PAR2K module is a ControlLogix 2-Port DH+ Communication Interface module. It provides two DH+ communication ports for connecting ControlLogix controllers to DH+ networks. The module supports communication rates up to 57.6 kbps and can be used with ControlLogix 1756-L6x and 1756-L7x controllers. It is commonly used for connecting ControlLogix systems to legacy DH+ networks for communication with devices such as PLC-5 controllers or other DH+ capable devices.