The number of transaction timeouts show the number of times that the node failed to receive expected acknowledgments or responses after retrying the configured number of times. These may be due to destination nodes being inaccessible on the network, transmission failures because of noise on the channel, or if any destination node has insufficient buffers or receive transaction records.
When using Request/Response service or network variable polling, a transaction timeout can also occur if the destination node application program does not return to the scheduler frequently enough, because responses are synchronized with the application tasks.