Detection of errors in the communication of data
The invention relates to a method and a system for detecting errors in the communication of data from a transmitter to at least one receiver. In the method, in a first step on the side of the transmitter a first check value is generated at least from user data to be communicated; in a second step on the side of the transmitter a second check value is generated at least from the user data and the first check value; in a third step at least the user data, the first check value and the second check value are communicated to the receiver; in a fourth step on the side of the receiver the communicated user data and the communicated first check value are verified with the aid of the second check value; and in a fifth step on the side of the receiver the communicated user data are verified with the aid of the first check value. To improve the detection of errors in the communication of data from the transmitter to the at least one receiver it is proposed that, in the first step, the user data are modified to generate the first check value, in the second step the unmodified user data are used to generate the second check value, in the fourth step the unmodified communicated user data are used, and in the fifth step the communicated user data are modified according to the modification in the first step for checking with the aid of the first check value.
1. A method of detecting errors in a communication of user data from a transmitter to at least one receiver, comprising:
providing non-modified user data to be communicated;
modifying the user data according to a modification rule;
determining a first check value at a transmitter side based on the modified user data;
determining a second check value at the transmitter side based on the non-modified user data and the first check value;
transmitting the non-modified user data and the first and second check values to the receiver;
verifying at a receiver side the transmitted non-modified user data and the first check value using the second check value;
modifying the transmitted non-modified user-data using the modification rule to form modified received user data; and
verifying at the receiver side the modified received user data using the first check value.
2. The method according to claim 1 , wherein the modification rule includes expanding the non-modified user data and the transmitted non-modified user data respectively.
3. The method according to claim 1 , wherein the modification rule includes re-arranging the non-modified user data and the transmitted non-modified user data respectively.
4. The method according to claim 1 , wherein the modification rule includes inverting at least part of the non-modified user data and the transmitted non-modified user data respectively.
5. The method according to claim 1 , wherein the first or the second check value is determined using a cyclic redundancy check.
6. The method according to claim 1 , wherein both the first and second check values are determined using an identical generation algorithm.
7. The method according to claim 1 , further comprising executing a security procedure if the verification of the transmitted non-modified user data or the verification of the modified received user data indicates a communication error.
8. The method according to claim 1 , wherein the method is implemented in a failsafe system to establish a communication between components of the failsafe system.
9. The method according to claim 1 , wherein the non-modified user data and the first and second check values are transmitted to the receiver via at least one field bus.
10. A system for detecting errors in a communication of user data from a transmitter to at least one receiver, comprising:
a transmitter having a first check unit for generating a first check value based on user data to be communicated and having a second check unit for generating a second check value based on the user data and the first check value;
a receiver; and
a transmission channel for transmitting the user data and the first and second check values from the transmitter to the receiver, the receiver having a first check mechanism for verifying the transmitted user data and the transmitted first check value using the second check value and having a second check mechanism for verifying the transmitted user data using the first check value, wherein
the transmitter includes a data modification algorithm for modifying the user data, wherein the first check value is determined from the modified user data, and
the receiver includes the data modification algorithm for modifying the transmitted user data, wherein the second check mechanism verifies the modified transmitted user data.
11. The system according to claim 10 , wherein the data modification algorithm includes expanding the user data.
12. The system according to claim 10 , wherein the data modification algorithm includes re-arranging the user data.
13. The system according to claim 10 , wherein the data modification algorithm includes at least partially inverting the user data.
14. The system according to claim 10 , wherein the first or the second check unit includes a cyclic redundancy check.
15. The system according to claim 10 , wherein the first or the second check unit includes an identical generation algorithm for determining the first and second check values.
16. The system according to claim 10 , further comprising a security unit for executing a security procedure if the first or the second check mechanism indicates a communication error.
17. The system according to claim 10 , wherein the system is part of a failsafe system having system components, the system establishing a failsafe communication between the system components.
18. The system according to claim 10 , further comprising a field bus for transmitting the user data.