Method for communication between a first passive subscriber and a second passive subscriber of a bus system

Patent metadata

Field	Value
Publication number	US-12212433-B2
Application number	US-202318178141-A
Country	US
Kind code	B2
Filing date	Mar 3, 2023
Priority date	Sep 29, 2020
Publication date	Jan 28, 2025
Grant date	Jan 28, 2025

Abstract

A method is provided for communicating between passive subscribers of a bus system. A first passive subscriber encodes an original static pattern in a first transmit SERDES element and encodes original user data in a time-synchronized manner with the original static pattern in a second transmit SERDES element. The second passive subscriber receives the encoded static pattern and user data, and generates a sampling clock having a first phase offset and a clock synchronous with a transmit-receive clock having a second phase offset, from the encoded static pattern. The second passive subscriber decodes the encoded static pattern using a first receive SERDES element and the encoded user data, using a second receive SERDES element to obtain a receive data word. The first receive SERDES element and the second receive SERDES element are operated based on the sampling clock, and the receive data word is output synchronously with the synchronous clock.

First claim

The invention claimed is:

1. A method for communicating between a first passive subscriber and a second passive subscriber of a bus system,
wherein a first differential double line and a second differential double line are used for the communication,
wherein an original static pattern with a predetermined bit length is transmitted via the first differential double line, wherein the original static pattern defines a transmit-receive clock,
wherein original user data are transmitted via the second differential double line, wherein the original user data comprise a transmit data word having the predetermined bit length,
wherein the first passive subscriber encodes the original static pattern in a first transmit SERDES element and transmits it via the first differential double line as an encoded static pattern to the second passive subscriber, and encodes the original user data synchronized in time with the original static pattern in a second transmit SERDES element and transmits it via the second differential double line to the second passive subscriber as encoded user data,
wherein the second passive subscriber receives the encoded static pattern and the encoded user data, wherein the second passive subscriber generates a sampling clock and a clock synchronous to the transmit-receive clock from the encoded static pattern,
wherein the sampling clock has a first phase offset with regard to the transmit-receive clock, wherein the synchronous clock has a second phase offset with regard to the transmit-receive clock,
wherein the second passive subscriber decodes the encoded static pattern with the aid of a first receive SERDES element and decodes the encoded user data with the aid of a second receive SERDES element, thus obtaining a receive data word, and
wherein the first receive SERDES element and the second receive SERDES element are operated based on the sampling clock, wherein the receive data word is output synchronously with the synchronous clock.

2. The method according to claim 1 , wherein the transmit-receive clock corresponds to one-tenth of a data rate transmitted over the first differential dual line or the second differential dual line, respectively.

3. The method according to claim 1 , wherein the sampling clock corresponds to the data rate transmitted via the first differential double line or via the second differential double line, respectively, or corresponds to half of the data rate transmitted via the first differential double line or via the second differential double line, respectively.

4. The method according to claim 1 , wherein the first phase offset is 90 degrees.

5. The method according to claim 1 , wherein the second phase offset is 18 degrees.

6. The method according to claim 1 , wherein the static pattern comprises a first number of first bits having a bit value of 1 and a second number of second bits having a bit value of 0, wherein in the static pattern, the first bits are arranged first and then the second bits are arranged, wherein the first number and the second number jointly correspond to the bit length.

7. The method according to claim 1 , wherein the static pattern decoded by the first receive SERDES element is shifted with the aid of a first shift register until the original static pattern is output at an output of the first receive SERDES element, and wherein the receive data word decoded by the second receive SERDES element is shifted with the aid of a second shift register by a number of bits identical to the first shift register.

8. The method according to claim 1 ,
wherein the encoded static pattern in the second passive subscriber is delayed by a first delay element and the encoded user data are delayed by a second delay element, and
wherein, during initialization, the delay of the first delay element and the second delay element is first gradually reduced and it is checked whether a sampled clock pattern changes and thus a lower limit for the delay is determined, subsequently increasing the delay of the first delay element and the second delay element in a stepwise manner and checking whether a sampled clock pattern changes and thus an upper limit for the delay is determined, and subsequently setting the delay of the first delay element and the second delay element to an average value of the lower limit and the upper limit.

9. The method according to claim 1 , wherein the user data is encoded and decoded using 8b10b encoding, wherein the predetermined bit length corresponds to 10 bits.

10. A first passive subscriber of a bus system, wherein the first passive subscriber comprises:
a first transmit connection for a first differential double line,
a second transmit connection for a second differential double line,
a first transmit SERDES element, and
a second transmit SERDES element;
wherein the first passive subscriber is configured to encode an original static pattern having a predetermined bit length in the first transmit SERDES element and to transmit it as an encoded static pattern via the first transmit connection, wherein the original static pattern defines a transmit-receive clock, and
is further configured to encode original user data in a time-synchronized manner with the original static pattern in the second transmit SERDES element and to transmit it via the second transmit connection as encoded user data, wherein the original user data comprise a transmit data word having the predetermined bit length.

11. A second passive subscriber of a bus system, wherein the second passive subscriber comprises:
a first receive connection for a first differential double line,
a second receive connection for a second differential double line,
a first receive SERDES element, and
a second receive SERDES element;
wherein the second passive subscriber is configured to receive an encoded static pattern having a predetermined bit length via the first receive connection and to receive encoded user data having the predetermined bit length via the second receive connection,
wherein the second passive subscriber is configured to generate a sampling clock and a clock synchronous with a transmit-receive clock from the encoded static pattern, the sampling clock having a first phase offset with respect to the transmit-receive clock, the synchronous clock having a second phase offset with respect to the transmit-receive clock, and
wherein the second passive subscriber is configured to decode the encoded static pattern with the aid of the first receive SERDES element and to decode the encoded user data with the aid of the second receive SERDES element to obtain a receive data word;
wherein the first receive SERDES element and the second receive SERDES element are operable based on the sampling clock, and wherein the receive data word is output synchronously with the synchronous clock.

12. The second passive subscriber according to claim 11 , wherein the second passive subscriber is configured to shift the static pattern decoded by the first receive SERDES element with the aid of a first shift register, until the original static pattern is output at an output of the first receive SERDES element, and to shift the receive data word decoded by the second receive SERDES element by a number of bits identical to the first shift register with the aid of a second shift register.

13. The second passive subscriber according to claim 11 , further comprising:
a first delay element between the first receive input and the first receiver SERDES element, and
a second delay element between the second receive input and the second receiver SERDES element,
wherein the encoded static pattern is delayable by the first delay element and the

Assignees

• Beckhoff Automation Gmbh

Inventors

• Kaulmann Tim
• Vonnahme Erik

Classifications

• H04L12/407 Primary

  with decentralised control · CPC title

• H04L12/40084 Primary

  Bus arbitration · CPC title