Buses are available for placement in the schematic editor only in one of the following ways.
- Choose Home | Circuit Elements | Bus from the main menus.
- Right-click in the design space then choose Place » Bus from the context menu.
After launching the command, the cursor will change to a cross-hair indicating bus placement mode. Placement is made by performing the following sequence of actions:
- Click or press Enter to anchor the starting point for the bus.
- Position the cursor then click or press Enter to anchor a series of vertex points that define the shape of the bus.
- After placing the final vertex point, right-click or press Esc to complete placement of the bus.
- Continue placing further bus objects or right-click or press Esc to exit placement mode.
- Use the Backspace or Delete key to remove the last bus segment placed.
Placement Modes
When placing a bus, there are three 'manual' placement modes, two of which have corner direction options. The modes specify how corners are created when placing buses and the angles at which buses can be placed.
During placement:
- Press the Tab key to pause the placement and access the Bus mode of the Inspector panel in which its properties can be changed on the fly. Click the design space pause button overlay (
) to resume placement.
- Press Shift+Spacebar to cycle through the three manual modes: 90°, 45°, Auto Wire, and Any Angle.
- While in the 90°or 45° mode (known as true orthogonal modes), press Spacebar to cycle between the corner direction options. In these modes, the line segment attached to the cursor is a look ahead segment – the actual segment being placed precedes this look-ahead segment.
- During placement, the current placement mode is displayed in the Status bar (at the very bottom of the design space). You can change modes at any time during Bus placement.
45 degree mode
90 degree mode
Any angle modePress Shift+Spacebar to cycle through the different placement modes.
Automatic Path Mode
An additional Bus placement mode is the Auto Wire mode, which can be used to route quickly from the previous segment end to the point where the cursor is clicked using the Point to Point Router. When enabled during the Shift+Spacebar selection cycle, this mode is indicated by a thick dotted line from the segment vertex to the cursor.
Placing a Bus segment in Auto Wire mode as indicated by the dotted path line. When placed (right), the Bus path will automatically avoid obstacles.
The path of the route will be the most efficient possible while avoiding existing placed objects on the sheet.
Electrical Snap
Along with its snap to grid feature, the schematic editor also supports snapping to available electrical connections. When an object is placed, such as a Bus, falls within a definable snap distance of a valid electrical connection, the cursor will jump to that electrical 'Hotspot' (shown as a blue cross).
The electrical snap point is indicated by a blue cross.
Electrical Object Hotspot snapping is configured in the
General region of the
Inspector panel when in
Document Options mode (accessed when no design objects are selected in the design space).
Graphical Editing
The graphical editing method allows a placed Bus object to be selected directly in the design space and its size and/or shape graphically changed.
When a Bus object is selected, the following editing handles are available:
A selected Bus ready for graphical editing
- Click and drag a non-handle point to reposition the entire Bus. When a Bus is not selected, click, hold and drag to reposition it.
- Click and drag A to reposition the end points of the Bus.
- Click and drag B to move a Bus vertex. The other vertices will remain anchored.
- Click and hold on a vertex then press Delete on the keyboard to remove that vertex.
With the Bus selected, click on a segment to individually select that segment. This Bus 'sub-selection' is distinguished by the associated editing handles becoming red in color.
Individual segment sub-selection
To clear the selection of (or de-select) the object, use the Esc key.
Non-Graphical Editing
This method of editing uses the Inspector panel mode to modify the properties of a bus object.
l
During placement, the Bus mode of the Inspector panel can be accessed by pressing the Tab key. Once the bus is placed, all options appear.
After placement, the Bus mode of the Inspector panel can be accessed in one of the following ways:
- If the Inspector panel is already open, select the bus object.
- With the bus selected, click View | Schematic | Inspector from the main ribbons.
Editing Multiple Objects
The Inspector panel supports multiple object editing, where the property settings that are identical in all currently selected objects may be modified. When multiples of the same object type are selected manually, an Inspector panel field entry that is not shown as an asterisk (*) may be edited for all selected objects.
Bus Connectivity
A Bus is used to bundle any number of nets. To do this, the following conditions must be met:
- Each individual net must be identified by a net label.
- The individual nets must be named using the standard naming pattern <Name><NumericalIdentifer1>, <Name><NumericalIdentifer2>, for example
Address0, Address1, ..., Address n.
- The Bus that the individual nets join must be identified by a net label, in the format <Name>[<StartingNumericalIdentifer>..<EndingNumericalIdentifier>], for example
Address[7..0], or LED[1..8].
Refer to the
Wire page for information about Net Labels.
Autojunctions
A T-junction in a Bus is automatically connected by a junction object. If the Break Wires At Autojunctions option is enabled on the Schematic - General page of the Preferences dialog, an existing Bus segment will be broken into two at the point where an autojunction is inserted. For example, when making a T-Junction, the perpendicular Bus segment will be broken into two segments, one on each side of the junction. With this option disabled, the Bus segment will remain unbroken at the junction.
For information about break wires, click
here.
Bus Entries
A bus entry is a short, diagonal section of wire that allows an individual net to be 'ripped' out of a Bus.
It also allows a net to be ripped out of a bus in the same location as another individual net is ripped out of the bus as shown in the image below. If a bus entry was not used in this situation, the two individual nets would connect together, creating a short-circuit. If it is not necessary to rip two individual nets from the same location on a bus, a standard Wire connection can be used.
Use bus entries when the nets need to be ripped from both sides of the Bus.
It is recommended that net labels on a Bus only contain alpha characters. For example, if you named the Bus D2[0..7], when the design is validated, this would be expanded to D20, D21 .. D27, which can potentially cause net name conflicts.
