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why did we get 3FF6206B warning?

we are using Ni-CAN card (driver v2.1) to talk with our haedware, it works fine,
except from time to time, the ncWrite pops up "3FF6206B warning",
I checked the doc, it says:
"CAN bus problems detected (no ack), but communication is
proceeding. This warning corresponds to CAN Error Passive
state. Solutions: Verify that cabling is correct, devices are
connected and operational, and proper bus power is applied. "

BUT, if one of cabling, connection, and proper bus power is not correct, the hardware shouldn't be operational,
the fact is that the hardware seems under fully control, the warning code is really annoying.
Why is that? how to fix it?
your help will be greatly appreciated!

James
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Hi James,

Warning code 0x3FF6206B (‘No Ack Warning’) is issued when a CAN node transmits a frame, but no other node in the network acknowledges that frame at the right time. The transmitter will re-attempt the transmission until some other node responds (acknowledges) that frame.
There are a couple of reasons why this warning would occur:
  • There is no listener (other CAN nodes) for the messages you’re trying to send
  • The listeners are not configured at the same baud rate
  • The listeners are all configured to not acknowledge incoming frames ('Listen Only Mode' - very unlikely)
  • There is really a problem with the cabling or termination of the network that causes a lot of mis-transmissions.
Can you tell from the other devices on the network, whether you are able to successfully transmit a single frame to those devices? I.e. do they indicate that they received something (e.g. status LEDs)?

-B2k
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