NI Matrix Switch Selection

[linu95k]

Hi,

I am trying to configure a system. I have an ECU which has a 120 pin connector two which I am connecting an different engines. Each engine pin to pin mapping to the ECU is different. For example, ECU Pin1 is mapped to Engine-1 Pin1, however for a different engine say Engine2, ECU Pin1 needs to be connected to Engine2 Pin4.

basically I am trying to create a reconfigurable matrix between the ECU & Engine connectors.

I am considering PXI Switches for the application.

However, I have never used PXI switches, thus I have the following queries:

1. What is the difference between Multiplexer Module for SwitchBlocks & PXI Switch Matrix Module?

2. If I want to configure 120 Pin input lines to 120 Pin output lines what matrix configuration would best suit my requirement?

3. I will be requiring 240 Pin in total, so if I use a 8x32 bit Matrix which can give me 256 crosspoints will it be suitable?

Thank you in advance

[crossrulz]

A matrix isn't going to do what you need here.  A matrix works by having rows and columns.  You connect signals to the columns and then make connections between columns using the rows (ex C1 and C2 connect to R1, which connects C1 and C2).

What you need is a 120 channel Form C (SPDT) relay bank.  A Form C relay has common (COM), normally open (NO), and normally closed (NC) pins.  When the relay is not activated, the COM is connected to the NC.  When the relay is activated, the COM is connected to the NO.  In your case, each signal would need its own relay.  The ECU signals would go to the COM pins.  One of the engines would go to the NC pins while the other engine goes to the NO pins.

If sticking with NI, you are probably looking at 2x of PXI-2571.  You should also check out Pickering.  You don't necessarily need to use PXI for this.  There are a few relay boards out there with a ton of capability.  For instance, Numato has a 64 channel USB relay board.

Regardless, make sure the current capacity of the relays can handle whatever your engine needs.

[JÞB]

There is one additional concern that you will need to address with your system.

Internal combustion engines move.  That is; they vibrate, bounce, torque and generally want to move stuff around (hey, it makes them useful!)

Relays hold there normally closed contacts closed to common with spring force and, when active, close common to normally open with an electromagnet.   They can "Bounce."

Make sure you design the mountings with that in mind and look at the shock and vibration specs for your Relays.   <Story time = TRUE> everything on the Komatsu Hybrid Excavator worked flawlessly in the HIL Lab and in field testing right up to scooping the first 65ton bucket full of ore.  Then the Relays bounced.  We had to replace them with an NI product.

[santo_13]

The answer is complicated.

If you want the ability to connect any of the 120 pins from ECU to any of the 120 pins to the connector, then you need a 120 x 120 matrix (14,400 crosspoints) which is huge. Sometimes the power lines are fixed and may not need a matrix routing at all, is this your case?

Do you need such extreme flexibility?

In your example, you can connect any of the 8 rows to any of the 32 columns making up the 8x32 matrix.

[Petru_Tarabuta]

Hi,

Pickering publish a useful booklet named SwitchMate. You can download it for free from: https://info.pickeringtest.com/pickering-switchmate-ebook .

They have a few other publications that you might find useful: https://www.pickeringtest.com/en-us/resources/publications 

[linu95k]

Using 2x 66 SPDT Relays Will allow me to only Map 132 ECU connector pins two 132 pin Engine connectors one connector being connected at NO side and another connector being connected at NC side which the physical pin mapping of the two connectors can be independent. 

The issue here is every time a new Engine is added i.e. new connector will have to be introduced with additional modules.

We wish to keep the routes from ECU side connector to Engine side connector re-configurable through software to avoid additional Hardware dependency. So that standard connectors one at ECU side and one at Engine side can be maintained.

[linu95k]

I am aware we can perform Row and column expansion with Switch Matrix modules. In case if I have to have to use 8x32 Matrix how can I expand this to accommodate my 120x120 requirement.

How should I be selecting the number of modules required based on which I will have to select a Chassis to accommodate the modules.