With various technologies available for design and test, compatibility can be a problem. One engineer recently faced the challenge of interfacing signals from an NI R Series terminal to an NI M Series terminal.
All the design files the engineer needs to complete this application (shown in Figure 1) are provided in the attached archive named 7328_custom_board.zip.
Figure 1. Creating a Custom Connector Board
2. The Need
At National Instruments, the R&D and marketing teams worked to address this engineer’s challenge. They had difficulty connecting various signals to an NI FPGA board with an R Series (68-pin) connection because the data acquisition (DAQ) card had an M Series (68-pin) connection. To make a connection between the two and interface a signal to the FPGA board, the teams needed two 68-pin screw terminal connector blocks (SCB 68). To use the screw terminal block, the teams had to route wires from the R Series connection to the M Series connection. This resulted in a mess of wires, making testing, validation, and demonstration difficult.
The teams wanted a clean, efficient solution that the engineer could use to connect R Series to M Series connectors while getting rid of the two SCB 68 connectors and the mess of wires. Their solution was a compact custom connector board that replaced the exposed wires.
In this article, learn about the creation of a PCB designed specifically to take a 68-pin R Series connector and interface the signals to an M Series connector. This user case was completed with NI Multisim and Ultiboard software.
3. NI Multisim Capture and Design
Multisim is an integrated schematic capture and simulation design environment that engineers use for its short learning curves, ease of use, and powerful application of SPICE simulation. The Multisim environment consists of a large work area to place and connect components as well as integrated measurement instruments and analyses to perform simulation.
Download the attached 7328_custom_board.zip file and extract to a folder on your computer.
Designing the Custom Connector Board
To create a connector board, engineers can use Multisim to define a schematic. They must connect from a 68-pin R Series connector and divert the signals to their appropriate destinations on an M Series connector.
The pin mapping from each connector type is shown in Figure 2.
Figure 2. Multisim Schematic Design – R Series to M Series
To rebuild this schematic, you must:
- Open Multisim by selecting Start»All Programs»National Instruments»Circuit Design Suite 10.1»Multisim 10.1
- Create a custom 68-pin connector schematic component (for an R Series connector in Figure 3a)
- Create a custom 68-pin connector schematic component (for an M Series connector in Figure 3b)
- Define the schematic
Figure 3. Custom 68-Pin Connectors for R Series (a) and M Series (b)
Both 68-pin connectors are created already and available in the attached Connector.prz file. A prz file is a database format engineers can use to export Multisim and Ultiboard components, which they can merge into another user's database.
The Connector.prz file adds new components to your Multisim database. Begin by opening the Multisim environment (Start»All Programs»National Instruments»Circuit Design Suite 10.1»Multisim 10.1).
- Double-click on the Connector.prz file.
- In the Database Merge dialog box, select a Target Database or User Database.
- Click on the Start button.
- Click on the OK button.
- Close the Database Merge dialog once the merge has completed.
These connectors are now available in the Multisim environment for use in a design.
To place the components in a Multisim schematic:
- Select Place.
- Select Component.
- In the Select a Component dialog box, select the User Database in the Database drop-down.
- Select the Basic group in the Group drop-down.
You now see the custom family of components that has been created in your Multisim database. This family contains the R Series and M Series components.
- Select the Connectors family.
- Select the 68-M-Series connector component.
- Click on the OK button.
- Place the connector on the schematic.
- Repeat steps 6 to 13 to place the 68-R-Series component in the same Connector family.
You now can connect the two components, as seen in Figure 2, to map the pins (and signals) from the R Series connector to an M Series connector. This is all done within a modeless wiring environment, which makes design quicker and easier.
To help you implement the steps in this article, you can simply open the attached RtoMConverter (MandF) 2.ms10 file, which contains the completed design.
4. Prototype Layout and Routing
The layout environment of Ultiboard is integrated with Multisim. Ultiboard equips the engineer with flexible tools to take a completed Multisim schematic and define part placement, copper routing, and finally export industry-standard Gerber files for prototyping.
Exporting a Schematic to Ultiboard
You now can transfer the RtoMConverter (MandF) 2.ms10 file to Ultiboard. To do this:
- Select Transfer»Transfer to Ultiboard 10.
- In the Save As dialog box, browse to the desktop.
- Save the file to the default name, which is RtoMConverter (MandF) 2.ewnet.
- Click on the Save button.
- Ultiboard automatically opens. You must now adjust various default settings for the design.
- In the Default Trace Width and Clearance dialog box, select the default settings. Click the OK button.
- The Import Netlist Action Selection imports all the various nets into Ultiboard. Click the OK button to import all nets from the Multisim schematic.
- The black Ultiboard background populated by the connectors with the various wire connections between now appears. The board outline has also been drawn (Figure 4).
At this time, you can begin defining the part placement and copper routes.
Figure 4. Design Exported to Ultiboard
Completing a design is the result of standard steps that require knowledge of PCB design and best practices in part placement and copper routing. This level of design is covered in the article Best Practices for Printed Circuit Board Routing, which offers information on the best practices for creating copper routes by using various manual and automated tools.
Investigating the Connector Board
For the remainder of this article, the previously discussed Multisim file, RtoMConverter (MandF) 2.ms10, has already been transferred to Ultiboard, and the copper routes have been defined.
- Open Ultiboard by selecting Start»All Programs»National Instruments»Circuit Design Suite 10.1»Ultiboard 10.1.
- Open the attached RtoMConverter(MandF)_Shorter.ewprj file to see the completed PCB design (Figure 5).
Figure 5. Completed Connector Board
This design is a four-layer board that consists of a Copper Top, Copper Bottom, and two inner layers named Bottom Buildup 1 and Bottom Buildup 2. You can see these layers in the Design Toolbox on the left-hand side of the Ultiboard screen (as seen in Figure 6). The layers in Ultiboard separate the various elements of the design. This means that surface mount components are placed onto either the top or bottom layers of the board. You can design and manipulate the board outline on another layer.
Figure 6. NI Ultiboard Design Toolbox
Notice in this design that there are multiple images and text blocks (such as LabVIEW FPGA). These are all placed onto the Silkscreen Top layer. These elements of the prototype design are used to convey product information and other pertinent information visually.
Viewing the Design in 3D
A helpful Ultiboard feature in the final design of a PCB is the 3D view. With this feature, you can effectively view the dimensions of the board in a virtual environment.
To view the design in 3D:
- Select Tools»View 3D.
- A dialog appears to inform you that the current font choice may cause increased use of the CPU and memory demand (Figure 7). For this example, select No to see the chosen font in the design.
Figure 7. View the Design in 3D Warning Dialog
- In this view, you can rotate and view the board in a 3D form (as seen in Figure 8).
- You can now expand the board view into its various layers. This view provides an X-ray-like view of the various pins, copper routes, and inner layers of the board. Select the Toggle Internal Layers View icon (seen in Figure 9).
- Rotate and view the expanded internal layers of the board (as seen in Figure 10).
Figure 8. The Connector Board as Seen in the 3D View
Figure 9. Expand the board to see the inner layers.
Figure 10. An X-Ray-Like View into the Properties of the Connector Board
For more information on how to use the 3D view in Ultiboard, read Viewing a PCB Design in 3D.
By using the 3D view and assessing the various pins, copper routes, and other board-level design information, you can assess the quality of your design. If complete (as is the design in Figure 9), you are ready to export the necessary files to physically prototype.
5. Exporting Files to Prototype the Board
Having finalized the design, now export the files so you can use them to fabricate the physical prototype. Within the attached zip file, find Converter Board.zip. This archive contains all the Gerber files, drill files, and so on to fabricate a board.
To export the Gerber files for yourself, simply follow these steps:
- Close the 3D View.
- Select File»Export.
- Select Gerber RS-274x. This is the industry-standard format for the fabrication of PCBs.
- Select Properties.
- Select all of the layers in the Available Layers field and click on the Right arrow. These layers are now exported.
To learn more about exporting Gerber files, read Exporting a Gerber File from NI Ultiboard.
6. The Completed Board
You can see the final fabricated board (with silkscreen imagery, vias, copper routes, and so on) in Figure 11. This small board is the result of straightforward, methodical standard steps; however, this board has a powerful purpose in completing the various elements of a design or test platform.
In this example, you simply interfaced the signal from one terminal connector to another. However, you can easily modify what happens in between these terminals. You can design signal conditioning such as filtering and amplification in Multisim as well as simulate it to verify its behavior.
This article represents the foundation of platform completion with Multisim and Ultiboard. Using this approach, the NI R&D and marketing teams were able to meet an engineer's challenge. Take advantage of the flexibility and ease of use of National Instruments design tools to bridge the gap between different design and test equipment.
Figure 11. Completed Connector Board Design