Use this tab page to define the parameters of each of the element's connection ports. The number of connections on an object varies, of course, depending on the object: a Duct take-off has just one connection port, but a Duct Wye has three.
Use the pop-up to switch among the connections, and edit each of them separately. In this image, we have selected the “Branch” connection from the pop-up on Duct Wye’s Connections tab page.
Note that the 2D Symbol object preview on the Preview and Positioning panel gives you feedback (the triangle) on which connection you are editing: in this case, the Branch of the Duct Wye.
Wall Thickness: This is the thickness of the MEP element’s wall.
Connection Type: Choose a Connection Type as applicable. For example, a ductwork element’s connection can either be simple or flanged. If you choose Flanged, enter a value for its width in the field below.
MEP System: If the element is generally used with multiple MEP systems (e.g. heating/cooling), then the MEP System pop-up is found on the Connections tab page. Use it to assign an MEP System (defined at Design > MEP Modeling > MEP Systems or Options > Attributes > MEP Systems) to the currently selected connection. (In contrast, single-function elements - such as bends - are assigned a single MEP System attribute on their General Settings tab page.)
Note: The regular ARCHICAD library includes MEP-compatible Library parts, such as plumbing fixtures, which have connection ports that connect smartly to MEP elements. To display these MEP connections, enable the Model View Option to Show Object MEP Connections. (Document > Model View > Set Model View, and go to the Miscellaneous Settings for Library Parts panel).
See also Behavior of MEP-Compatible Objects.