# The TFC Connection

Connections can be established between the various components. For example, a tenon joint or an end-face joint can be created between posts and sills/frames. This has always been possible by setting the desired connection at each location. There are two problem situations with these connections:

* If you want to change a connection, you must make the same modification at every location in the HRB file where that connection is used.
* The connection always originates from the "abutment" component, in our example above from the post. If, however, the post terminates at several components, a problem arises because only one connection can be set at each end per abutting component. Posts in particular often need to connect to multiple sills or frames.

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Both issues can be solved using the HRB connection. The HRB connection has been available since version 22.01 and offers the following advantages:

* It is defined centrally.
* It allows the combination of operations.
* With the introduction of the HRB connection, clear rules for searching components were also implemented.

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The HRB connection is defined centrally in the basic information of the HRB file. Using the top toggle you can switch between the different HRB connections. Each defined HRB connection can, as before, be saved under any name and managed via the manage icon.

In the next line you can enter a designation for the HRB connection. This will then be displayed in the tree at the left edge of the screen, making it easier to locate the desired HRB connection.

With the maximum extension for searching you can set by how much the respective member may be extended to find a connection partner. More detailed information about this search is described here: Component search for connections

Since an HRB connection can contain multiple connections, the next toggle allows you to switch between the connections of the current HRB connection. The HRB connection in the image above contains 2 connections and we see the first of the two connections. If a third connection is to be added, switch with the toggle to the second connection and click once more. The next connection will then be created automatically.

Each connection consists of the connection itself (T-joint end plate, end-face joint, tenon, section,...), a condition and the component filter:

* Connection: You select a saved setting that determines the type of connection and its dimensions.
* Condition: Because you can access the formula editor here and therefore all available user and system variables, complex "calculations" and conditions can be set. The HRB connection is executed only if this condition is met.
* Component filter: With the component filter you determine which connection components are searched for this connection. Fill only the fields necessary for the filter and leave the remaining fields empty.\
  In the example above members with member type 621/sill and 622/frame are searched.\
  Additionally there is a special criterion that allows you to determine the orientation (rotation) of the connection components relative to member 1 of the connection. You set whether the width of member 1 is parallel to the:

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* Width of member 2: If you enter a member without rotation (rotate cross-section: 0.0°), then the width of the member in the wall is always the surface that you see in the wall view. In the top illustration the lowest sill and the posts are entered without rotation. With the 'Width of member 2' option you can therefore connect the posts to all non-rotated sills.
* Height of member 2 (rotated): As the addition 'rotated' indicates, components that are rotated relative to member 1 are taken for connection here. In the top illustration this allows the posts to be connected to the rotated (vertical) sills.

An important point when defining the connections within an HRB connection is the order in which the connections are defined! As soon as the program finds a member 2 for which the filter rule applies, member 1 is connected to that member 2. That member 2 is then considered connected and is effectively checked off. It will no longer be considered for any further connection, even if it would match the filter rule of another connection. Therefore, you should start with the finer (more specific) filter rules and then, if necessary, use coarser filter rules for other connections.
