QNX RTOS v4 Knowledge Base
QNX RTOS v4 Knowledge Base
| Title |
error: 'collision det heartbeat not txed' |
| Ref. No. |
QNX.000009499 |
| Category(ies) |
Network |
| Issue |
What causes this error message on a network?
|
| Solution |
The description for the 8390 register that triggers this for some
cards reads:
"CD HEARTBEAT: Failure of the transceiver to transmit a collision signal after transmission of a packet will set this bit. The Collision Detect (CD) heartbeat signal must commence during the first 6.4 us of the Interframe Gap following a transmission. In certain collision, the CD Heartbeat bit will be set even though the transceiver is not performing the CD heartbeat test."
Ignoring the last sentence, this means that when listening for the slot the right thing wasn't heard. There is some evidence to suggest this can happen on a very busy ethernet, but more commonly happens when the cable is pulled out of the wall. |
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