PXI 2567/6132

[Leslie0101]

Good day,

I'm making a PCB that utilizes the PXI 2567 and PXI 6132.

For the PXI 2567:

I want to know if I can connect all the common grounds together. Specifically:

Common Ground Return CH0:7     (pin 42)

Common Ground Return CH8:15   (pin 3)

Common Ground Return CH16:23 (pin 66)

Common Ground Return CH24:31 (pin 27)

Common Ground Return CH32:39 (pin 51)

Common Ground Return CH40:47 (pin 12)

Common Ground Return CH48:55 (pin 75)

Common Ground Return CH56:63 (pin 36)

GND (pin 39)

For the PXI 6132:

I also want to know if I can connect the Analog Input grounds together. Specifically:

AI 0 GND (PIN 67)

AI 1 GND (PIN 32)

AI 2 GND (PIN 64)

AI 3 GND (PIN 29)

AI 4 GND (PIN 27)

AI 5 GND (PIN 59)

AI 6 GND (PIN 24)

AI 7 GND (PIN 56)

The question is because each ground belongs to specific channels, and we want to know if we can connect them all to a common ground plane. We have checked the documentation for these PXI cards but we're still not clear.

Thanks in advance for any help,

Leslie 

[Sean_N]

As far as the 6132 goes, there should be no issue connecting all of the channel grounds together.  Because this device is simultaneous sampling, each channel has its own analog-digital converter.  The reason they have separate grounds is for channel-channel isolation.  You will lose this isolation, but I don't believe that there will be an issue.

With regards to the 2567, I'm not sure how you plan to drive your relays, but if each channel was using the same source, then this shouldn't be an issue.  If you are using multiple sources, you will more than likely need to keep the common grounds separate.  How do you plan on driving relays?  I can check into this if you let me know what you plan to use as your voltage source.

Thanks,

Sean

[Leslie0101]

Thanks for your reply. I'm working on a break out board (PCB) that will utilize both modules. We are only making the connections available to the user's daughter board, and the user will decide how to use them.

I already talked by phone with an engineer from NI, and she recommended me to leave all the grounds separate from each other, but she didn't explain the reason.

Thanks,

Leslie

[Sean_N]

Leslie-

An engineer from R&D saw your post and thought there could be a little clarification.

-The 2567 only has one gnd (several ground pins, but internally they are all grounded together).  The 2567 also has a 5V and a 12V INTERNAL drive voltage that you can use to drive relays (with limited current). Alternatively, you can use an external relay driver, but it has to share the ground with the 2567 (if they use two drivers then they both have to share the same ground).

-We would recommend against sharing the 2567's ground on the PCB with the 6132's because the 2567's is going to be a lot more noisy and carry a significant amount of current.  You want to keep the AI grounds clean so we would recommend two different grounds on the PCB.  One for all AI channels labeled "AI GND" , and one for the 2567 labeled "Relay Driver GND."

I hope this clarifies any remaining issues!

Thanks,

Sean

[SKant]

Hi Sean,

How u doing?

I am facing one issue with using pxi-2567 . In our project there is 20 relays based DI and I am using DAQmx for drive the relay . I fined one relay switch example i.e.. Switch_Controlling_Individual_Relay for drive the external relay. But there is flickering in relays or LED.

Also I want to use Switch_Controlling_Individual_Relay vi as a subVI to my main VI to operate multiple relay, but its not working i.e..  i'mnot getting making contact o/p  from subVI. 

So,please help me here to resolve this issue ASAP.

Regards,

Srikant

[Luke_B]

Hi Srikant,

When you mentioned that the led is flickering, what led were you talking about?

The example, Switch Controlling Individual Relay begins by resetting the switch, so if you had closed any relays, calling this vi would immediately return all relays to their default state, open. If you are calling this VI multiple times, that may explain why you are seeing flickering.

This example vi was also not intended to be used as a sub-vi, it was meant to demonstrate how to use the DAQmx vi's and what inputs they require. I'd suggest using the DAQmx vi's directly in your application. You can use the "DAQmx Switch Close Relays.vi" to close one or more relays. It is the vi used in the example you mentioned.

The DAQmx Switch vis can be found on the Functions Palette under Measurement I/O>>NI-DAQmx>>Dev Config>>Switches

I also wanted to check if you were driving the relays from the onboard +5V or +12V sources, or if you were using an external power supply. You will want to make sure you aren't trying to get more current than the power source can provide if you are trying to close 20 relays.

Hopefully this points you in the right direction,

Regards,

[sats]

Hello,

I am working on resource optimization project using PXI 2567. We have five different vibration experiments, in this 3 electromagnets & 2 Dc motors are actuators and 5 accelerometers are sensors. My intension is within less no. of channels can i achive sensing and actuation, like currently i need 3 Digital out insted of 3 can i achive with 2 digital output. With actuators there will be no issue but incase of accelerometers can switch resources. I am not clear about by using PXI 2567 can i switch AI (Acclerometers)..Please give me suggestions.

Thanks in advance..

Regards,

Satish

[Izzzzz]

Hello Satish,

To get a clear understanding of what you are trying to accomplish I need to ask some clarifying questions.

1. Are you currently using the PXI-2567 in your application?
2. What are the accelerometers connected to and how are you measuring their output?
3. You mentioned that the accelerometer could switch resources, could you please elaborate on this statement.  
4. The 2567 is typically created to drive relays with up to 50 volts or 600mA of drive (with your own external supply) thus I do not see how this module applies to your accelerometers.
5. I will need more information about your application in order to recommend possible steps to take.

Regards,

Izzy O.

Applications Engineer

National Instruments