1. Matrix Size
Matrix size is often described as M rows by N columns (M x N) configurations. Some common configurations are 4 x 64, 8 x 32, and 16 x 16. Because of its flexible architecture, a matrix is also easily inverted, whereby rows become columns and columns become rows. You achieve this simply by how you wire the matrix. For example, a 4 x 64 matrix can be made into a 64 x 4 matrix. This knowledge is especially useful in matrix selection, because it can save you time and money in certain cases.
With some modules, you can partition a matrix into several smaller configurations within the module. For example, you can create dual or quad configurations, which respectively provide you with two or four smaller matrices in a single module. Some common examples of partitioned matrices include dual 4 x 32, dual 8 x 16, and quad 4 x 16 configurations.
2. Terminal Block Configurations
Using NI PXI matrix switch modules, such as the PXI/PXIe2532B, you can configure each matrix as several different 1wire and 2wire matrix configurations through the use of terminal blocks. In fact, the PXI/PXIe2532B is capable of twelve different matrix topologies when used with seven different terminal blocks. The following table describes some example configurations you can readily achieve using the corresponding matrix module and terminal block. For more information on topology options for any particular NI switch module, reference the devices section of the NISWITCH Help Documentation.
Matrix Size

Terminal Block

4 x 128 1Wire

TB2640B

8 x 64 1Wire

TB2641B

16 x 32 1Wire

TB2642B

Dual 4 x 64 1Wire

TB2643B

Dual 8 x 32 1Wire

TB2644B

Dual 16 x 16 1Wire

TB2645B

Quad 4x32 1Wire

TB2646B

Sixteen 2x16 1Wire

No TB Needed

4x64 2Wire

TB2643B

8x32 2Wire

TB2644B

16x16 2Wire

TB2645B

Dual 4x32 2Wire

TB2646B

3. Matrix Expansion
Matrix modules can also serve as building blocks for creating larger configurations that are well beyond the size of a single module. Column expansion is the process of connecting each row between two or more matrix modules, effectively doubling the number of columns within the expanded matrix. Alternatively, row expansion is the process of connecting each column of two or more matrix modules, doubling the number of rows within the expanded matrix. Some NI matrix modules offer cable or terminal block solutions for easy matrix expansion, such as the PXI/PXIe2532B, PXI2535, PXI2536, or PXI2541, making matrix expansion a simple task by simply connecting purchasable accessories.
Additionally, the NI SwitchBlock is a flexible, carrierbased matrix expansion system, designed for creating large matrices from individual matrix cards without additional cabling. The NI SwitchBlock carrier plugs in to a PXI chassis and then individual matrix cards are inserted into the SwitchBlock carrier, which provides another easy way to combine individual matrices into a larger matrix. For more information on SwitchBlock, read the NI SwitchBlock white paper.
Other PXI matrix modules require manual matrix expansion using bare wires between terminal blocks or custom cables, which isn’t as easy as a prebuilt solution.
The following section is a compilation of frequently asked questions (FAQs) in regard to expanding a PXI matrix switch module.
4. Matrix Switch Expansion FAQs
How do I determine the number of modules my matrix requires?
For the purpose of this example, assume your application requires a 14 x 184 matrix and that you have chosen to create it with 8 x 32 matrix modules. These are the steps:
1. Determine the matrix size of a single switch module. (8 x 32)
2. Divide the number of rows desired by the number of rows in a single module. Then round up the answer. (14 / 8 = 1.75) » 2 modules
3. Divide the number of columns desired by the number of columns in a single module. Then round up the answer. (184 / 32 = 5.75) » 6 modules
4. Multiple the values found in steps 2 and 3 to determine the number of modules required by your matrix. (2 x 6 = 12, which creates a 16 x 192 matrix)
How do I expand the number of rows?
You can row expand a matrix by connecting the columns of multiple matrix modules to expand/increase the number of rows in your matrix. The following diagram connects two 4 x 64 matrix modules to create a single 8 x 64 matrix by connecting the 64 columns of each module.
Figure 1. Expand the number of rows in a matrix by connecting columns.
How do I expand the number of columns?To perform column expansion, you can connect the rows of the modules to expand/increase the number of columns in your matrix. The following diagram connects two 4 x 64 matrix modules to create a single 4 x 128 matrix by only connecting the four rows of each module.
Figure 2. Expand the number of columns in a matrix by connecting rows.
How do I physically expand the matrix?
You can physically expand any matrix by using individual wires to connect the terminals of one module to the terminals of another module, but this can become very tedious as your matrix size increases. For example, to build 128 x 16 matrix out of eight 16 x 16 matrix modules would require additional time to manually connect 224 wires.NI addresses this cumbersome process by offering effortless matrix expansion solutions for column expansion of some matrix modules. For example, you can connect multiple PXI2532B matrix modules with expansion cables to expand column count.
For more information on matrix expansion options for other switch modules, please reference the devices section of the NISWITCH Help Documentation.
5. Matrix Expansion Examples
Example 1.
Create a 4 x 256 (2wire) matrix with the PXIe2532B using the TB2643B terminal block. The TB2643B configures each PXIe2532B as an individual 4 x 64 2wire matrix.
Solution:
Using the steps provided earlier, identify the number of modules you will need:
 For 4 rows, you will need only one module (4 / 4 = 1)
 For 256 columns, you will need four modules (256 / 64 = 4)
Therefore, you will need four (1 x 4 = 4) PXIe2532B modules to build the desired matrix architecture, as well as the same number of TB2643B terminal blocks. You will also need three ribbon cables to connect the row connection headers of each terminal block as shown below.
Figure 3. Use the row connection headers and ribbon cables to expand the number of columns available.
Example 2.
Create a 8 x 180 (1wire) matrix with the PXI2536. Each PXI2536 is an individual 8 x 68 1wire matrix.
Solution:
Each PXI2536 has three connectors, one dedicated to column connections, one for row connections in, and another for row connections out. You can use the row connection out connector and stock SHC68C68S cable to connect to other PXI2536 matrix modules.
 For 8 rows, you will need one module (8 / 8 = 1)
 For 180 columns, you will need three modules (180 / 68 = 2.65 >> 3)
Figure 4. Use the row in and row out connectors to expand the number of columns available.
Example 3.
Create a 8 x 36 RF matrix (300 MHz bandwidth) with the PXIe2541 RF matrix module. Each PXIe2541 is an individual 8 x 12 RF matrix.
Solution:
Each PXI2541 has MCX connectors for each column, row in, and row out. You can use the row out connectors to connect to other PXIe2541 matrix modules using MCXtoMCX cables. When building RF switching systems, it is important to keep cables as short as possible to conserve signal integrity.
 For 8 rows, you will need one module (8 / 8 = 1)
 For 36 columns, you will need three modules (36 / 12 = 3)
Figure 5. Use the row in and row out connectors to expand the number of columns available.
Example 4.
Create a 32 x 32 (2wire) matrix with the PXIe2739 matrix module. Each PXIe2739 is an individual 16 x 16 2wire matrix.
Solution:
 For 32 rows, you will need two modules (32 / 16 = 2)
 For 32 columns, you will need two modules (32 / 16 = 2)
Figure 6. Schematic of a 32 x 32 2wire matrix built with PXIe2739 modules.
6. Related Links
For more information on NI switch offerings, please visit the following resources:
 NI SwitchBlock for Large Matrix Systems
 Matrix Expansion Guide for SCXI Switch Modules
 How to Choose the Right Relay
 Understanding Switch Topologies