Protocol for communications in potentially noisy environments
A communications protocol that is designed for transmission of data in networks that are subjected to harsh conditions is described herein. A network includes a plurality of devices, where the devices comprise respective nodes. The nodes are in communication with one another by way of a central network hub. The protocol causes the nodes to transmit data over a network bus at different data rates depending upon whether the nodes are operating normally or an arbitration procedure has been invoked.
1. A network system comprising:
a transmitting node that transmits data at a first rate in accordance with a communications protocol, the transmitting node comprises a pin;
a receiving node that receives the data and processes the data in accordance with the communications protocol; and
a hub that is in communication with the transmitting node and the receiving node, the hub receives the data from the transmitting node and directs the data to the receiving node at the first data rate, wherein when the transmitting node has completed transmission of the data, the transmitting node initiates an arbitration procedure in accordance with the communications protocol and transmits a request to the hub at a second data rate, the second data rate being slower than the first data rate, the request being a request to transmit additional data, wherein the pin of the transmitting node is tied to ground to indicate that a third node in the network system is prohibited from receiving the data.
2. The network system of claim 1 , wherein the first data rate is at least double the second data rate.
3. The network system of claim 1 , the transmitting node and the receiving node being field programmable gate arrays that are configured to communicate with one another by way of the communications protocol.
4. The network system of claim 1 , further comprising a first device that comprises the transmitting node and a second device that comprises the receiving node, the first device comprises a first application that generates the data transmitted by the transmitting node, the second device comprises a second application that consumes the data received by the receiving node.
5. The network system of claim 4 , the transmitting node generates a first cyclic redundancy check (CRC) value based upon the data and transmits the first CRC value with the data to the receiving node.
6. The network system of claim 5 , the receiving node receives the data and generates a second CRC value based upon the data, the receiving node, in accordance with the communications protocol, compares the first CRC value with the second CRC value.
7. The network system of claim 6 , wherein the receiving node identifies that the first CRC value is equivalent to the second CRC value, and transmits an acknowledgement to the transmitting node responsive to identifying that the first CRC value is equivalent to the second CRC value.
8. The network system of claim 6 , wherein the receiving node identifies that the first CRC value is different from the second CRC value and transmits an indication to the transmitting node that a packet that comprises the data has been rejected by the receiving node.
9. The network system of claim 1 , further comprising a test module that is in communication with the hub, the test module monitors all network traffic that flows through the hub.
10. The network system of claim 1 , wherein the transmitting node transmits an indication that the data is to be broadcast to all nodes in the network system.
11. A method executed by a node in a network system, the method comprising:
receiving data generated by an application that is in communication with the node, the data is to be transmitted to a second node in the network system;
responsive to receiving the data, generating a data packet in accordance with a communications protocol, the data packet comprises a header and a payload, the data included in the payload;
responsive to receiving the data, initiating an arbitration process, wherein initiating the arbitration process comprises transmitting a request to a central hub at a first data rate;
responsive to initiating the arbitration process, receiving confirmation from the hub that the node is able to transmit the data packet; and
responsive to receiving the confirmation, transmitting the data packet at a second data rate, the second data rate being higher than the first data rate, wherein the node comprises a pin that is tied to ground to indicate that a third node in the network system is prohibited from receiving the data packet.
12. The method of claim 11 , wherein the second data rate is at least double the first data rate.
13. The method of claim 11 , wherein a difference between the first data rate and the second data rate is based upon lengths of cables in the network system.
14. The method of claim 11 , wherein generating the data packet comprises:
computing a cyclic redundancy check (CRC) value for the data; and
including the cyclic redundancy check in the payload of the data packet.
15. The method of claim 11 , the node being one of a field programmable gate array or an application specific integrated circuit that is configured to transmit and receive data in accordance with the protocol.
16. The method of claim 11 , wherein the header of the data packet comprises data that identifies the second node and data that identifies an application of the second node that is to consume the data from the first node.
17. The method of claim 11 , wherein the confirmation received from the hub comprises data that identifies the node.
18. A node in a network that is subjected to a harsh environment, the node configured to execute a protocol for transmission and receipt of data over the network, the protocol configured to cause the node to perform a plurality of acts when transmitting or receiving data, the acts comprising:
transmitting a request for control of a network bus to a network hub, the request transmitted at a first data rate;
receiving confirmation from the network bus that the node has control of the network bus; and
responsive to receiving the confirmation, transmitting data over the network bus at a second data rate, the second data rate being higher than the first data rate, wherein the node comprises a pin, the pin of the node is tied to ground to indicate that a second node in the network system is prohibited from receiving the data.
19. The node of claim 18 , the acts further comprising:
prior to receiving the confirmation from the network hub, refraining from transmitting data over the network bus.