Creating Bus Vectors in Multisim

Publish Date: Sep 06, 2006 | 3 Ratings | 5.00 out of 5 |  PDF

Overview

Today’s engineers require sophisticated tools to match the increasing complexity of their designs. Specifically, as pin counts and trace counts increase, designers turn to buses to logically organize their connections.

Multisim delivers powerful bus-vector connectivity. Not only can you easily draw buses with a few clicks of the mouse, but you also have to intuitive methods for creating connections both to and among buses.

Additionally, buses can be linked across pages of complex designs or to the inputs and outputs of Hierarchical Blocks and Subcircuits.

There are two bus wiring modes: busline mode and net name mode. In net name mode, buslines take on the name of the nets connected to them, whereas in busline mode, buslines have unique names.

These tips apply only to busline mode, which is the default mode. To switch between modes, use the Wiring tab of the Sheet Properties dialog box.

Once a bus has been created, you can add new buslines and tap into them as many times as you need to manually. Additionally, you can add new buslines automatically using the Bus Vector Connect tool, and automatically tap into them as many times as you need to using the same tool.

Table of Contents

  1. Placing a Bus
  2. Manually Connecting Buslines
  3. Automatically Creating New Buslines
  4. Automatically Connecting to Existing Buslines

1. Placing a Bus

To place and wire a bus follow the steps listed below:

1. Click on the bus tool from the components toolbar (Ctrl-U).
Bus Wire Toolbar Icon


2. Click on the beginning location and intermediary vertices to create the bus. Double click on the last vertex to complete the bus, or right click to end the bus without placing a final vertex. The bus is now ready to be tapped. Buses can also have 45 degree angles.

Tip: To ensure that automatic connections to this bus will wire in an aestethically pleasing manner, keep the bus close to the component(s) to which it will connect.

Bus Ready to be Tapped

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2. Manually Connecting Buslines

To manually connect to a bus:

1. Left click on a source pin
2. Move the mouse cursor next to the desired bus location. A ghosted bus tap line will appear.
3. Left click to place the bus tap.
Manually Tapping into a Bus


4. A dialog box will appear, prompting you to enter the name of this particular busline. Enter the desired name, and click Ok to continue.
Bus Entry Connection Dialog


The completed busline appears on the schematic.
Completed Busline

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3. Automatically Creating New Buslines

You can use the bus vector connect tool to automatically create any number of buslines at the same time. This is an extremely useful feature for large numbers of connections.

With at least one bus present in your design, follow the steps below to automatically create new buslines.

1. Right-click on the component to which you would like to connect the bus.

2. Choose "Bus Vector Connect" from the right-click menu.
Bus Vector Connect Menu Option


3. The bus vector connect dialog box will appear.

In the component section of this dialog (a. of the figure below), choose the side of the component symbol that contains the pins that connect to the bus. In this example, the desired lines are on the bottom of the component.

Now choose the pin(s) to connect to the bus (b. of the figure below). Hold the Ctrl or Shift keys to select multiple pins.

Lastly, click the down arrow icon to add these pins to the intermediary section of the dialog.


Bus Vector Connect Dialog

4. Now choose the desired bus from the Bus Name pull-down box. Click Auto-assign to create new buslines that will connect to the selected component.

Tip: The bracketed dashes indicate that no other connections exist between that busline and components in your design.


Bus Vector Connect Dialog

5. A dialog appears asking you to to choose the section of the bus where the buslines should connect. Click OK, then choose the desired section of the bus. Multisim will then automatically wire the from the chosen component to the selected bus.


Dialog Prompting for Bus Segment Selection

Completed Bus

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4. Automatically Connecting to Existing Buslines

Once you have used the Bus Vector connect tool to automatically create buslines, you will want to connect "the other end" of those buslines. You can tap into a busline any number of times.

1. Right click on the destination component, and choose "Bus Vector Connect".

2. From the Bus Vector Connect dialog box, again choose the side of the component that contains the pins which you would like to connect to the bus.

3. Select the desired pins from the Pins section of the dialog box, then click the down arrow icon to place them in the intermediary section of the dialog.

Tip: Use the Ctrl and Shift keys to select multiple pins.

4. Choose the desired bus from the Bus Name pull-down. Select each of the existing buslines, and then click the down arrow icon to add them to the intermediary section of the dialog.

5. Use the Up and Down buttons to match up the component pins with the desired buslines. The pins on the left side of the intermediary section will be automatically connected to the existing buslines on the right side of the intermediary section. Click OK when finished.
Matching Component Pins to Existing Buslines


Multisim will automatically tap into the bus, matching the component pins you selected, with the existing bus lines you chose in the Bus Vector Connect dialog box.
Completed Bus

Related Links:
Multisim Evaluation Software

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