PXI-8512 - Am I able to set the signal voltage for CANH and CANL lines?

[vacuumtube6l6]

From the spec doc:

CAN_H, CAN_L bus lines voltage

-27 VDC to +40 VDC

Can I generate a CAN signal inside this voltage range or the equipment is just able to handle these values when receiving some CAN messages?

Thanks.

[DMycroft]

Hello,

The PXI-8512 is using a TJA1041 high speed CAN transceiver, the specs of the transceiver can be found here. 

For the future you can find the chips inside any modules on the spec sheet of the module its self. I found the transceiver chip under Physical Characteristics here.

My understanding is, the chip can receive voltages in the range of -27 VDC to +40 VDC, as long as the potential difference of CAN_L and CAN_H is within the ranges shows in the spec sheet.

With regards to signal generation, I believe this is driven by the power method used. Sorry I don't have a concrete answer, I believe you will find what you're looking for in the TJA1041 spec sheet.

Thanks,

Dom

[DMycroft]

HI,

I have been doing some more digging and my understanding is that the PXI-8512 can NOT generate signals in this range.

What you're referring to in the spec sheet is not the signal generation range, but rather the absolute maximum ratings for the pins:

• The -27V to +40V range represents the absolute maximum voltages that the CANH and CANL pins can tolerate without permanent damage to the device. These are survival ratings, not operational ratings.
• The actual operational voltage levels that the TJA1041 generates during normal CAN communication are still the standard CAN levels (approximately 2.5V to 3.5V for CANH and 2.5V to 1.5V for CANL).

The wide voltage tolerance range is important because:

1. It provides protection against transients and fault conditions that might occur in automotive environments
2. It allows the device to survive potential shorts to battery or ground
3. It provides robustness in noisy electrical environments where voltage spikes can occur

So while the TJA1041 can survive exposure to voltages from -27V to +40V, it doesn't actively generate signals at those extreme voltage levels during normal operation.

Hope this helps, let me know if you need any more info.

Thanks,

Dom

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