RIO Evaluation Kit - Voltage range for Encoder Channles

[TIMondragon]

Hi,

Could you help us about where to find the documentation to know the voltage range of the 2 Encoder Channels, A and B of the NI LabView RIO Evaluation kit? 

Thank you!

[Bob_Schor]

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@TIMondragon wrote:

Could you help us about where to find the documentation to know the voltage range of the 2 Encoder Channels, A and B of the NI LabView RIO Evaluation kit?

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I'm not sure what you want to know.  Are you looking for information about quadrature encoding using the NI myRIO?  Do you have the myRIO Software Toolkit installed?  I don't currently have a version of LabVIEW 2019 or 2021 installed (which are, I believe, the last two versions of LabVIEW that support the myRIO Software Toolkit), but I'm quite sure that the A and B Quadrature Encoder channels expect TTL signals, digital signals where High is +5 V and Low is 0 V.  There are other NI modules (including USB multifunction devices) that have Counter/Timer inputs that also use TTL signals for counter A and B inputs.

Try doing a Web search for LabVIEW Rotary Encoder or similar wording.

Bob Schor

[rolfk]

Actually the digital IO on the myRIO and other sbRIO hardware are 3.3V digital logic. They may be 5V tolerant but better check the datasheet about that. Otherwise you may blow the pins after some time if you connect them to full 5V signals.

[Bob_Schor]

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@rolfk wrote:

Actually the digital IO on the myRIO and other sbRIO hardware are 3.3V digital logic. They may be 5V tolerant but better check the datasheet about that. Otherwise you may blow the pins after some time if you connect them to full 5V signals.

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Oops.  So I checked the myRIO manual (we have one at the heart of a multi-channel stimulator we built).

    DIO <0..7> DGND Input or Output
    General-purpose digital lines with 3.3 V output, 3.3 V/5 V-compatible
     input. Refer to the DIO Lines section for more information

We haven't had any blow up on us (so far), but I'll point this out to the team.

Bob Schor

[rolfk]

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@Bob_Schor wrote:

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@rolfk wrote:

Actually the digital IO on the myRIO and other sbRIO hardware are 3.3V digital logic. They may be 5V tolerant but better check the datasheet about that. Otherwise you may blow the pins after some time if you connect them to full 5V signals.

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Oops.  So I checked the myRIO manual (we have one at the heart of a multi-channel stimulator we built).

    DIO <0..7> DGND Input or Output
    General-purpose digital lines with 3.3 V output, 3.3 V/5 V-compatible
     input. Refer to the DIO Lines section for more information

We haven't had any blow up on us (so far), but I'll point this out to the team.

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Well, it says 5V compatible. That means you are allowed to connect external 5V signals to a pin configured as input. It does however only output 3.3V max, usually 2.8 to 3 V so if you use it as an output your external hardware better sees 2.7V as logic high. For TTL compatible inputs that would work but CMOS inputs might not.

But that all should be checked for other sbRIO hardware explicitly too before assuming anything.