Creating a Custom R-Series to M-Series Connector Board with NI Multisim and NI Ultiboard

For modern design, test and validation solutions, there is a need to be able to customize the platform for specific applications. For effective communication, transfer of data, signal conditioning, or simply to connect two pieces of hardware, an off-the-shelf solution is not always available for your application.

Whether signals interface to data acquisition devices (DAQ, CompactDAQ) or designs platforms (such as embedded design through CompactRIO or the LabVIEW Embedded Module for ARM), the fact remains that in many use cases custom amplification, filtering, or conversion is required for appropriate conditioning.

Engineers therefore require a custom printed circuit board (PCB) in order to complete their platform. In order to easily build such a PCB many test and design engineers need to be able to deploy tools that do not require steep learning curves. The National Instruments Circuit Design Suite equips the engineer with the tools to quickly prototype such PCBs, with the easy-of-use and powerful circuit design of NI Multisim and the flexible layout of NI Ultiboard.

Platform completion is increasingly becoming a necessary stage of design and test system implementation. Off the shelf solutions are not always available, particularly as designs become ever more complex, and integrate elements from various vendors.

Introduction

With various technologies available for design and test, compatibility can prove to be an issue. One such problem recently encountered for an engineer was to interface signals from a R-Series terminal to a M-Series terminal.  

All design files needed to complete this application (pictured in Figure 1) are provided in the attached archive named 7328_custom_board.zip.

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Figure 1: Creating a Custom Connector Board

 

The Need

Here at National Instruments, the R&D and marketing team were having difficulty connecting various signals to a NI FPGA board. The FPGA board had a R-Series (68-pin) connection. The data acquisition (DAQ) card had a M-series (68-pin) connection. In order to make a connection between the two and interface a signal to the FPGA board, two 68-pin screw terminal connector blocks (SCB 68) were required. The screw terminal block, meant wires had to be routed from the R-series connection to the M-series connection. This resulted in a mess of wires, making testing, validation and demonstration difficult.

What was needed was a clean, efficient solution which allowed the engineer to connect R-Series to M-Series connectors while replacing two SCB 68 connectors, and the mess of wires. The solution is a compact custom connector board which replaced the exposed wires.

In this article you will explore the creation of such a PCB designed specifically to take a 68 pin R-Series connector, and interface the signals to a M-Series connector. This user case was completed with NI Multisim and NI Ultiboard.

 

NI Multisim Capture and Design

Multisim is an integrated schematic capture and simulation design environment, chosen by engineers for ease-of-use, quick learning curves, 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.

Interactively to learn how to use the capture and simulation features of Multisim

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, Multisim can be used to define a schematic.  You must connect from a 68 pin R-Series connector and divert the signals to their appropriate destination on a M-Series connector.

The pin mapping from each connector type can be seen in Figure 2 below.

Figure 2:  Multisim schematic design, R-Series to M-Series

 

In order to re-build this schematic you must:

• Open Multisim be selecting Start > All Programs > National Instruments > Circuit Design Suite 10.1 > Multisim 10.1.
• Create a custom 68 pin connector schematic component (for a R-Series connector in Figure 3a)
• Create a custom 68 pin connector schematic component (for a 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 in which you can export Multisim and Ultiboard components, which can be merged into another users database.

The Connector.prz file will add 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).

1. Double-click on the Connector.prz file.
2. In the Database Merge dialog box select a Target Database of User Database.
3. Click on the Start button.
4. Click on the OK button.
5. Close the Database Merge dialog once the merge has completed.

These connectors are now available to you in the Multisim environment to be used in a design.

To place the components in a Multisim schematic:

6. Select Place.
7. Select Component.
8. In the Select a Component dialog box select the User Database in the Database drop-down.
9. Select the Basic group in the Group drop-down.

You will now see the custom family of components that has been created in your Multisim database. This family contains the R-Series and M-Series component.

10. Select the Connectors family.
11. Select the 68-M-Series connector component.
12. Click on the OK button.
13. Place the connector on the schematic.
14. Repeat steps 6 to 13 to place the 68-R-Series component in the same Connector family.

The two components can now be connected as seen in Figure 2, to map the pins (and signals) from the R-Series connector to a M-Series connector. This is all done within a modeless wiring environment, which makes design quicker and easier.

To make following this article easier you can simply open the attached RtoMConverter (MandF) 2.ms10 file, which contains the completed design.

 

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

We can now transfer the RtoMConverter (MandF) 2.ms10 file to Ultiboard. To do this:

1. Select Transfer > Transfer to Ultiboard 10
2. In the Save As dialog box, browse to the desktop.
3. We will save the file to the default name, which is RtoMConverter (MandF) 2.ewnet.
4. Click on the Save button.
5. Ultiboard will automatically open. You must now set various default settings for the design.
6. In the Default Trace Width and Clearance dialog box, select the default settings. Click the OK button.
7. The Import Netlist Action Selection imports all the various nets into Ultiboard. Click the OK button to import all nets from the Multisim schematic.
8. You will see the black Ultiboard background populated by the connectors with the various wire connections between. The board outline has also been drawn (figure 4)

At this time we are ready to begin defining the part placement and copper routes.

Figure 4: Design Exported to Ultiboard

 

Completing a design, is a result of standard steps that require knowledge of PCB design and best practices in part placement and copper routing. Since this level of design is outside the scope of this article, it is suggested that you view the following article on the routing stages of design: Best Practices for Printed Circuit Board Routing. This article will provide you with information on the best practices of creating copper routes by using the various manual and automated tools available to you.

 

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.

1. Open Ultiboard by selecting Start > All Programs > National Instruments > Circuit Design Suite 10.1 > Ultiboard 10.1.
2. 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 4 layer board, consisting of a Copper Top, Copper Bottom and two inner layers, named Bottom Buildup 1 and Bottom Buildup 2. These layers can be seen in the Design Toolbox in 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 will be placed onto either the top or bottom layers of the board. The board outline can be designed and manipulated on another layer.

Figure 6: NI Ultiboard Design Toolbox

 

You will notice in this design that there are multiple images and text (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 feature of Ultiboard that can be helpful 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:

1. Select Tools > View 3D.
2. A dialog will appear, informing 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

3. In this view you can now rotate and view the board in a 3D form (as seen in Figure 8).
4. 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).
5. 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 it is suggested that you view the following article: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.

 

Exporting Files to Prototype the Board

Having finalized the design, it is time to export the files so that they can be used to fabricate the physical prototype. Within the attached zip file, you will notice the Converter Board.zip file. This archive contains all the Gerber files, drill files etc… in order to fabricate a board.

To export the Gerber files for yourself you simply need to:

1. Close the 3D View.
2. Select File > Export.
3. Select Gerber RS-274x. This is the industry standard format for the fabrication of PCBs.
4. Select Properties.
5. Select all of the layers in the Available Layers field, and click on the Right arrow. These layers will now be exported.

To learn more about exporting Gerber files, view the following article: Exporting a Gerber File from NI Ultiboard.

 

The Completed Board

The final fabricated board (with silkscreen imagery, vias, copper routes etc…) can be seen in Figure 11 below. This small board is the result of a straight forward, methodical standard steps. However this board has a powerful purpose in completing the various elements of a design or test platform.

In this example we simply interfaced the signal from one terminal connector to another, however what happens in between these terminals can be easily modified. Signal conditioning such as filtering and amplification can be designed in Multisim, and simulated to verify its behavior.

This article represents the foundation of platform completion with NI Multisim and NI Ultiboard. Taking the ease-of-use and flexibility of National Instruments design tools to bridge the gap between different design and test equipment.  

Figure 11: Completed Connector Board Design

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