Method for determining the topology of a serial asynchronous databus
First Claim
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1. A method for determining the topology of a serial asynchronous data bus, to which at least a first bus subscriber and a second bus subscriber are connected, which subscribers communicate via a prescribed bus access protocol that comprises defined request and response telegrams, the method comprising:
- sending request telegrams from the first bus subscriber and receiving the request telegrams at the second bus subscriber,sending a respective response telegram from the second bus subscriber in response to each request telegram, and receiving the response telegrams at the first bus subscriber,determining, at a first measurement site positioned on the data bus on a side of the first bus subscriber opposite the second bus subscriber, a first plurality of time differences between the reception of a particular request telegram of the first bus subscriber and the reception of a respective related response telegram of the second bus subscriber,determining, at a second measurement site positioned on the data bus on a side of the second bus subscriber opposite the first bus subscriber, a second plurality of time differences between the reception of the particular request telegram of the first bus subscriber and the reception of the respective related response telegram of the second bus subscriber, andcalculating a first average response time Tres1 for the second bus subscriber, from the determined first plurality of time differences,calculating a second average response time Tres2 for the second bus subscriber from the determined second plurality of time differences,calculating a run time delay TL as half of the difference between the first average response time Tres1, and the second average response time Tres2, thus enabling deduction of a distance between the first bus subscriber and the second bus subscriber.
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Abstract
A computer-implemented method for determining the topology of a serial asynchronous data bus, to which at least a first bus subscriber and a second bus subscriber are connected, which subscribers communicate via a prescribed bus access protocol.
32 Citations
17 Claims
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1. A method for determining the topology of a serial asynchronous data bus, to which at least a first bus subscriber and a second bus subscriber are connected, which subscribers communicate via a prescribed bus access protocol that comprises defined request and response telegrams, the method comprising:
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sending request telegrams from the first bus subscriber and receiving the request telegrams at the second bus subscriber, sending a respective response telegram from the second bus subscriber in response to each request telegram, and receiving the response telegrams at the first bus subscriber, determining, at a first measurement site positioned on the data bus on a side of the first bus subscriber opposite the second bus subscriber, a first plurality of time differences between the reception of a particular request telegram of the first bus subscriber and the reception of a respective related response telegram of the second bus subscriber, determining, at a second measurement site positioned on the data bus on a side of the second bus subscriber opposite the first bus subscriber, a second plurality of time differences between the reception of the particular request telegram of the first bus subscriber and the reception of the respective related response telegram of the second bus subscriber, and calculating a first average response time T res1 for the second bus subscriber, from the determined first plurality of time differences,calculating a second average response time T res2 for the second bus subscriber from the determined second plurality of time differences,calculating a run time delay TL as half of the difference between the first average response time T res1, and the second average response timeT res2, thus enabling deduction of a distance between the first bus subscriber and the second bus subscriber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method for determining the topology of a serial asynchronous data bus, to which at least a first bus subscriber and a second bus subscriber are connected, which subscribers communicate via a prescribed bus access protocol that comprises defined request and response telegrams, wherein the first bus subscriber comprises a master unit, and the second bus subscriber comprises a slave unit, the method comprising:
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(a) the master unit sends a request telegram to the slave unit at a transmission point in time T0, (b) a measurement unit located on the serial bus on a side of the master unit opposite a side of the slave unit, receives the request telegram and at the next clock pulse edge generates a first time stamp ZS, (c) the slave unit receives the request telegram after a run time TL, which is a function of the distance between the master unit and slave unit, wherein the request telegram has a length of x bit times, (d) after reception of the request telegram is complete and a waiting time of y bit times has elapsed, the slave unit sends a response telegram, (e) after the run time TL the master unit receives the response telegram at a point in time TE, (f) the measurement unit receives the response telegram and at its next clock pulse edge generates a second time stamp ZE, and (g) from the difference between the two time stamps a response time T res, which is associated with the master unit, is determined, andwherein the acts (a) to (g) are repeated a number of times, wherein spreading of response times which occurs as a result of variations in the waiting time of the slave unit is cancelled out by means of an average value algorithm for the calculation of an average response time T res1 from the determined multiple response timesT res1.
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Specification