CN104092515B - CAN bus communication method compatible with CAN2.0B protocol - Google Patents
CAN bus communication method compatible with CAN2.0B protocol Download PDFInfo
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Abstract
The invention discloses a CAN bus communication method compatible with a CAN2.0B protocol. According to the method, an enhanced CAN protocol, namely an ECAN protocol is adopted for communication; the ECAN protocol is a protocol obtained after redefining the CAN2.0B protocol; the ECAN protocol enables nodes which adopt the ECAN protocol for communication to conduct communication at a higher speed than nodes which adopt the CAN2.0B protocol for communication, and also enables the nodes which adopt the ECAN protocol for communication to coexist with the nodes which adopt the CAN2.0B protocol for communication in the same network. By means of the CAN bus communication method, the communication speed is increased, and meanwhile the nodes which adopt the ECAN protocol for communication can coexist with the existing nodes conforming to the CAN2.0B standards in the same network, so that the compatibility is good.
Description
Technical field
The present invention relates to industrial control field, more particularly to a kind of CAN communication means of compatible CAN2.0B agreements.
Background technology
CAN is a kind of many main process equipments local that BOSCH companies are designed for Hyundai Motor electronic equipment interconnected communication
Net, its remarkable performance have been widely used for numerous occasions such as Industry Control, the vehicles, Medical Instruments, Digit Control Machine Tool.
BOSCH companies issued the CAN2.0 rule of the CAN2.0B agreements comprising CAN2.0A and 29 ID with 11 ID in 1991
Model, but with the increase of application demand, its highest 1Mbps traffic rate can not meet application demand, therefore BOSCH exists
The CAN FD1.0 agreements with higher traffic rate are issued within 2012, although the agreement can be lifted based on CAN FD agreement sections
Traffic rate between point, but cannot the compatible existing node based on CAN2.0B agreements.In other words, it is only used for building
The brand-new network based on CAN FD agreements, therefore need badly a kind of compatible with CAN2.0B nodes and reach higher traffic rate
Technological means.
The content of the invention
It is an object of the invention to the above-mentioned deficiency in the presence of overcoming prior art, there is provided a kind of compatible CAN2.0B associations
The CAN communication means of view, which improves logical between CAN network node on the premise of compatible existing CAN2.0B agreements
Letter speed.
In order to realize foregoing invention purpose, the technical solution used in the present invention is：A kind of CAN of compatible CAN2.0B agreements
Bus communication, using enhancement mode CAN protocol, i.e. ECAN protocol communications；Wherein, the ECAN agreements are that CAN2.0B is assisted
The agreement after redefining is discussed, and the ECAN agreements cause CAN2.0 protocol communications to be adopted using the node ratio of ECAN protocol communications
Node there is the communication that higher speed realizes between node, while so that the node of the employing ECAN protocol communications can be with
Same network is coexisted in using the node of CAN2.0B protocol communications.
The present invention retains all other frame class in addition to physical-layer data frame of BOSCH companies CAN 2.0B consensus standards
Type, frame format, response mechanism, false judgment and error count mechanism, and the institute of other physical layer communications being related to
There is method, only change the frame format of its physical-layer data frame and high ratio is inserted by the data field in CAN2.0B frames and CRC domains
Special mode realizing the lifting of traffic rate, while realizing and coexisting in same net using the node of CAN2.0B protocol communications
Network.
The ECAN agreements are specifically configured to：On the basis of CAN2.0B, retain its each field and to redefine which long-range
Framing bit RTR, reserved bit R0 and R1 distinguishing CAN2.0B Frames and ECAN Frames, the definition of ECAN arbitrations by agreement domain and
Corresponding arbitration mechanism is identical with CAN2.0B agreements；In the data field corresponding to CAN2.0B agreements and CRC domains in ECAN agreements
Interior filling high-speed bit data realize the lifting of transfer rate, and the filling of the high-speed bit data meets CAN2.0B agreements
Bit padding rule.
In one embodiment of the invention, the filling of the high-speed bit data adopts following first method：
Last " R " of one group of every 3 bit is completely used for transmitting high-speed bit, if the transfer rate of high-speed bit is
CAN2.0B Bit Transmission RatesTimes, then can transmit per 3 CAN2.0B bitsThe user data of bit, N are not little
In 1 integer.
In another embodiment of the present invention, the filling of the high-speed bit data adopts following second method：First
On the basis of mode, in addition to first group, the sync section of " R " bit of per group of beginning and phase section are deducted and synchronously redirect width S JW
Time be used for transmitting high-speed bit, increase transfer rate.
In another embodiment of the invention, the filling of the high-speed bit data is in the following ways：In second method
On the basis of, the phase section for increasing per group " D " bit deducts the synchronous time for redirecting width S JW for transmitting high-speed bit,
Further to increase transfer rate.
New Frame is we term it ECAN Frames, meet the CAN node quilts of new frame and corresponding response mechanism
Referred to as ECAN nodes.
Compared with prior art, beneficial effects of the present invention：Enhancement mode CAN protocol is adopted in the present invention between network node,
That is ECAN protocol communications, ECAN agreements are the agreement after redefining to CAN2.0B agreements, and the ECAN agreements cause to adopt
The node ratio of ECAN protocol communications there is higher speed to realize the communication between node using the node of CAN2.0 protocol communications,
Cause the node of the employing ECAN protocol communications coexist in same net with using the node of CAN2.0B protocol communications simultaneously
Network.Therefore, the present invention on the premise of the node of compatible existing employing CAN2.0B protocol communications is improve and is assisted based on CAN
Traffic rate between the network node of view.
Description of the drawings：
Fig. 1 is CAN 2.0B and ECAN physical-layer data frame structural representations；
Fig. 2 is that ECAN vertical frame dimensions speed bit data fills three kinds of method schematic diagrams.
Specific embodiment
With reference to specific embodiment, the present invention is described in further detail.But this should not be interpreted as the present invention
The scope of above-mentioned theme is only limitted to below example, and all technologies realized based on present invention belong to the model of the present invention
Enclose.
It is contemplated that on the premise of the node of compatible existing employing CAN2.0B protocol communications, improve based on CAN
Traffic rate between the network node of agreement.
The CAN communication means of compatible CAN2.0B agreements provided in an embodiment of the present invention, using enhancement mode CAN protocol,
That is ECAN protocol communications；Wherein, the ECAN agreements are the agreement after redefining to CAN2.0B agreements, the ECAN agreements
So that using ECAN protocol communications node ratio using CAN2.0 protocol communications node have higher speed realize node it
Between communication, while so that the node of the employing ECAN protocol communications can with coexisted using the node of CAN2.0B protocol communications
In same network.
For convenience, in the present invention, self-defined enhancing Frame is ECAN（Enhancement CAN）Frame, the present invention
In involved frame data description（The state description of such as signal, recessive position Recessive- abbreviation R, dominant bit
Dominant- abbreviation D etc.）With CAN2.0 agreements（Robert Bosch GmbH. CAN Specification, Version
2.0. 1991）Definition it is identical, in other words the present invention only the Frame of CAN2.0 is redefined, other it is all in
Hold identical with BOSCH CAN2.0 specifications.Meanwhile, for convenience, the present invention in " CAN2.0 " refer to BOSCH CAN2.0A and
CAN2.0B agreements（Robert Bosch GmbH. CAN Specification, Version 2.0. 1991）Defined
Content, " CAN2.0A " refer to basic model BOSCH CAN2.0A（11 ID）, " CAN2.0B " refers to extended pattern BOSCH CAN2.0B（29
Position ID）.
The present invention retains all other frame class in addition to physical-layer data frame of BOSCH companies CAN 2.0B consensus standards
Type, frame format, response mechanism, false judgment and error count mechanism, and the institute of other physical layer communications being related to
There is method, only change the frame format of its physical-layer data frame and high ratio is inserted by the data field in CAN2.0B frames and CRC domains
Special mode realizing the lifting of traffic rate, while realizing and coexisting in same net using the node of CAN2.0B protocol communications
Network.
The invention reside in the physical-layer data frame of CAN2.0B agreements is redesigned, with the speed higher than CAN2.0B node
Realize new node（I.e. using the node of ECAN agreements）Between communication, while these new nodes can be with CAN2.0B nodes altogether
Same network is stored in, realizes that the node based on the data frame format is compatible with existing CAN2.0B nodes, will weight in the present invention
The physical layer data frame structure of newly-designed CAN2.0B agreements and mechanism are referred to as enhancement mode CAN communication agreement, abbreviation ECAN associations
View, the CAN nodes for meeting new ECAN frame structures definition and corresponding response mechanism are referred to as ECAN nodes.
For the frame structure of ECAN, only the Frame of CAN2.0B is redesigned, remote frame, erroneous frame, overload frame
And interframe space is identical with CAN2.0B standards.In enhanced communications, in order to improve traffic rate, in the base of CAN2.0B
On plinth, retain its each field and redefine its long-range framing bit RTR, reserved bit R0 and R1 to distinguish CAN2.0B Frames
With ECAN Frames, ECAN arbitrations by agreement domain defines and corresponding arbitration mechanism is identical with CAN2.0B agreements；In ECAN agreements
The lifting that high-speed bit data realize transfer rate, the high speed is filled in data field and CRC domains corresponding to CAN2.0B agreements
The filling of bit data meets the bit padding rule of CAN2.0B agreements.I.e. CAN2.0B agreements data field and CRC domains adopt
Realized ensureing the bit padding rule of CAN2.0B nodes while high-speed bit is transmitted with variable Rate mode（Can not occur connecting
Continue 6 identical values）And correct synchronization control can be carried out（Retain interval i.e. in ECAN frame structure designs short same enough
Step edge）, to realize compatibility.
ECAN Frames frame format and CAN 2.0B data frame formats are as shown in Figure 1.For CAN2.0B frames, 101 is its frame
Opening flag position SOF, 102 is its arbitration domain, and 103 is long-range framing bit RTR, and 104,105 and 106 are respectively in its control domain
Reserved bit R1, R0 and DLC, 107 be data field, 108 be CRC, 109 be CRC delimiters, 110 and 111 be respectively response bits
ACK and ACK delimiters, 112 is End of Frame EOF.
For ECAN frames, its arbitration domain 114 is identical with CAN2.0B frames, and the RTR positions of CAN2.0B frames are defined as 115 only is
Reserved bit R1, and send dominant bit " D ", therefore for ECAN frames are without remote frame, in the use of ECAN, remote frame by
The remote frame of CAN2.0B is completing.In control domain, reserved bit R1 of CAN2.0B and R0 transmissions dominant bit " D ", ECAN is corresponded to
It is ECAN flags EDL defined in frame（116）With reserved bit R0（117）, the recessive position " R " of EDL transmissions, R0 transmissions dominant bit " D ",
Therefore 104 and 116 is the unique mark for distinguishing CAN2.0B frames and ECAN frames.106 and 118 DLC fields give subsequent transmission
The length of data, its concrete numerical value meet the regulation of CAN2.0B, and CAN2.0B nodes carry out data length according to CAN2.0B agreements
Explain, and ECAN nodes are then reinterpreted to transmission data length（It is specifically shown in explained later part）, therefore each DLC advised
Fixed CAN2.0B frames have all corresponded to an ECAN frame.The 107 of CAN2.0B frames corresponding with 108 time period the 119 of ECAN frames,
120 and 121 time periods, the user data of high-speed filling in 119,120 time periods in ECAN frames, is transmitted, so as to improving transmission
Speed.Wherein 121 for ECAN frames reception error identification, in CAN2.0B frame ratio identical with the bit-time of CAN2.0B
Specially for last bit of CRC, in ECAN frames by receiving terminal according to the ECAN data CRC check correctness for receiving sending
" D " or " R ".122（CRC delimiters）、123（ACK）、124（ACK delimiters）、125（EOF）With the 109 of CAN2.0B frames
（CRC delimiters）、110（ACK）、111（ACK delimiters）、112（EOF）Correspond, and with CAN2.0B identicals send out
Send rule.
Corresponding with the Frame of CAN2.0B agreements, ECAN Frames also contains frame and start（SOF）, arbitration domain（ID）, control
Domain processed（CONTROL）, data field（DATA）, cyclic redundancy check (CRC) domain（CRC）, Acknowledge（ACK）And End of Frame（EOF）.In Fig. 1
Dark parts are interval for the variable Rate of ECAN Frames, and it contains the data field of ECAN frames and CRC domains, ECAN Frames its
It is partly transmitted still according to the speed of CAN2.0B；SOF, ACK, ACK delimiter of ECAN frames and EOF and CAN2.0B are fixed
Justice is identical；Reserved bit R1 is revised as in the RTR positions of ECAN frames in arbitration domain, and transmits dominant bit " D "；Will in control domain
Reserved bit R1 of CAN2.0B frames is revised as EDL positions, and transmits recessive position " R ", distinguishes CAN2.0B and ECAN frames, EDLC with this
Field；CAN2.0B and ECAN frames node does different length and explains to DLC fields.CAN2.0B frame structures are repaiied by this
Change so that the transmission of high-speed bit data can be carried out during the data field of CAN2.0B and CRC domains, while in transmission at a high speed
CAN2.0B nodes during ECAN frames in network can carry out correct synchronous, bit padding error detection, to realize high speed ECAN
Frame and CAN2.0B frames coexist in same network, so as to the high-speed transfer and compatibility that solve CAN2.0B frames and CAN FD frames are asked
Topic.
As in variable Rate part, in network, existing CAN2.0B nodes gather high data rate with relatively low speed,
It is likely to occur random error.In order to prevent existing CAN2.0B nodes in network from sending bit padding in ECAN frame high rate partials
Mistake, then meet the excessive data of CAN2.0B agreements in the fixed position filling of ECAN frames high rate partial correspondence.Additionally, in order to
CAN2.0B nodes are allowed not produce frame format mistake, then existing CAN2.0B nodes then need the data for correctly parsing ECAN frames long
Degree, CRC delimiters, ACK domains and EOF.ECAN frames these about frame data format key position also with CAN2.0 standards
It is consistent.Therefore, the whole time duration of each ECAN frame is identical with the frame that CAN2.0B is defined, while in ECAN
The data length of DLC sections definition must be reinterpreted in frame（It is specifically shown in explained later part）.
ECAN frame structures are illustrated with reference to Fig. 1：
1）SOF：Frame start mark it is identical with CAN2.0B protocol definitions, be operated under the speed used by CAN2.0B,
Sending end is with from R（Reccessive, recessive position, logical one）To " D "（Dominate, dominant bit, or logical zero）Saltus step
Start as frame, receiving terminal completes initial than ultrahard synchronization when saltus step is detected.
2）Arbitration domain：In addition to reserved bit R1 that the RTR positions of CAN2.0B Frames have corresponded to ECAN, other portions in domain are arbitrated
Divide identical with CAN2.0B Frames with ECAN Frames.It is remote frame when RTR sends R in CAN2.0B frames, is number when sending D
According to frame, the R1 in corresponding ECAN frames sends D, thus defines ECAN frames without remote frame, and the function of remote frame to be realized then is needed
The mode of CAN2.0B to be utilized is realized.
Arbitration domain is used for bus arbitration, and the concrete distribution of ID needs system level to consider, distribution and the routine of ID
CAN2.0B bus arbitrations are identical, and some ECAN frames can be higher than the priority of CAN2.0B frame, and some then can be compared with
The priority of CAN2.0B frames is low.
3）Control domain：It is made up of 6 bit datas in control domain, specifically includes EDL：Reserved bit R1 pair of CAN2.0B nodes
The EDL positions of ECAN frame nodes are answered, has been D in CAN2.0B frames, be R in ECAN frame nodes, the position has been difference CAN2.0B frames
With the unique mark of ECAN frames.
R0：It is reserved bit in the enhancement frame of CAN2.0B, the position is D, and ECAN frames node entered using the saltus step of EDL to R0
Row is once hard synchronous, and CAN2.0B nodes are not made a decision to the position.
DLC：DLC is data length, totally 4, in CAN2.0B nodes and ECAN nodes does different explanations.Its value be 0～
8, the byte number of transmission is represented in CAN2.0B, the value more than 8 is interpreted 8.For ECAN frames, DLC sections will be done and solve again
Release, see the content of the ECAN frame data length explanations part of subsequent content.
Data field
For CAN2.0B frames, its length is user's transmission byte number that DLC specifies, for ECAN frames, its length sees below continuous
The ECAN frame data length of content explains the content of part.When application layer institute, transmitted bit number is less than the explained numbers for obtaining of ECAN
During according to length, first should fill in application layer, Filling power also includes the calculating of CRC.
It should be noted that in order to each ECAN frame it is uniquely corresponding with CAN2.0B frames, then should be in the fixed position of ECAN frames
Insertion bit, to avoid the CAN2.0B in the communication of ECAN frames from producing bit fill-error mark, is shown in data field with CRC domains
The description of fill method.
CRC domains:CRC domains include rapid rate and the two parts with CAN2.0B phase same rates.
CRC sequences：In order to increase valid data length, CRC using with the identical CRC algorithm of CAN2.0B agreements, it
Transmitted with rapid rate；But in the case where fill rule of the present invention is met, CRC can also change according to the actual requirements, using not
It is same as the multinomial of CAN2.0B agreements to generate CRC sequences, needs the data CAN2.0B regulation for carrying out CRC calculating consistent（I.e.
Include SOF, arbitration domain, control domain and data field）.
ECRC mistakes：When ECAN node receiving terminal crc checks do not find mistake, then the mark is during the instruction of ECRC mistakes
R is sent, when receiving terminal finds that CRC is not corresponded, then wrong passive ECAN frames receiving node sends R, and the ECAN frames of mistake active connect
Receive node and send D.In this way, equivalent to the wrong responses and error identification for individually carrying out ECAN frames.It is wrong that ECRC is set
It is that when ECAN frames are gathered, CRC error probabilities are big due to CAN2.0B nodes by mistake the reason for response, if finding mistake, according to
CAN2.0B agreements, will provide error identification after ACK delimiters.And ECAN nodes transmitting terminal may receive the response of ACK, but
Error identification is received again, it is impossible to is judged that the error identification is because real format error, is also come from CAN2.0B nodes.
This is set so that just can determine that the correctness of data before CAN2.0B responses.
CRC delimiters：CRC delimiters are the bit duration of a CAN2.0B speed, are worth for R, its definition with
CAN2.0B is consistent.ECAN frames node is the same with CAN2.0B nodes, also checks such as this kind of form error of CRC delimiters.
ACK slot：When receiving terminal is finished receiving, and CRC check is when passing through, and will send a D in the position.In ECAN
In frame traffic, it is very big that CAN2.0B nodes receive crc error probability, sends a R when crc error is found.And it is corresponding
ECAN nodes, as long as CRC check passes through, then send response D, otherwise send R.
ACK delimiters：Its definition with it is consistent in CAN2.0B agreements.
EOF:With it is consistent in CAN2.0B agreements.
Invention provides for a kind of enhancement mode CAN data frame format, can be, but not limited to using single-chip microcomputer, AISC,
The carriers such as FPGA are realizing.
Next illustrate the above-mentioned high-speed bit data filling method to ECAN data frame datas domain and CRC domains：
When the high rate partial of ECAN frames is transmitted, CAN2.0B nodes still monitor bus state, as CAN2.0B is saved
, with factors such as adjust automatically sampled point mechanism, the randomness of high-speed data, for CAN2.0B nodes, it will be in height for point
Fast part collects uncertain value, may destroy the fill rule of CAN2.0B.On the other hand, during frames in high speed transmission,
CAN2.0B nodes still carrying out the work such as bit synchronous, in particular cases re-synchronize what is brought to same direction
Error accumulation is likely to cause bit padding mistake.Therefore, the filling of bit stream should take into full account the factor of these two aspects, high speed number
According to transmission during should ensure from agreement that CAN2.0B nodes do not produce error identification to interrupt the transmission of high-speed data.
Additionally, the frame length of Frame should all correspond with its association from CAN2.0B nodes and ECAN frames node
View regulation.As CAN2.0B nodes have had related protocol to specify the meaning in its DLC domain, therefore ECAN frames enter on this basis
Row is reinterpreted, and is specifically shown in subsequent content " explanation of the ECAN frames to DLC fields " part.The Frame of CAN2.0B nodes and
ECAN frames are equal in time, and each ECAN frame has corresponded to a CAN2.0B frame.
The high-speed bit data filling method of the present invention, i.e. the three of ECAN frames kind high-speed bit data filling mode such as Fig. 2
It is shown.It is used for transmitting the filling of high speed after the DLC fields of CAN2.0B frames, before ECRC error bits.One CAN2.0B
Frame bit-time contains sync section SYN（201）, phase section 1（202）, phase section 2（203）.It is for three kinds of filling modes, first
First constant transmissions one " R " and " D " before " ECRC mistakes " bit, then from after DLC to the data before 201 according to 3
One group of individual CAN2.0B bits, per group of value are " R ", " D ", " R " mode arranging data.If the transmission data bit that DLC specifies
The integral multiple of number non-3, transmission " R " before 201 under a remaining bit case, 201 under remaining 2 bit case before transmission " R " and
“D”.Specifically there are implementations different in 3：
Mode 1, last " R " of one group of every 3 bit（207）It is completely used for transmitting high-speed bit, if high-speed bit
Transfer rate is CAN2.0B bit ratesTimes, then can transmit per 3 CAN2.0B bitsThe user data of bit.
Mode 2, on the basis of mode 1, in addition to first group, the sync section of " R " bit of per group of beginning and phase section 1 subtract
Desynchronize and redirect time of width S JW and be used for transmitting high-speed bit, that is, increase by 208 inserting high-speed bit.
Mode 3, on the basis of mode 2, the phase section 1 of " D " bit of per group of increase is deducted and synchronously redirects width S JW
Time transmits high-speed bit, the i.e. time of increase by 209 to transmit high-speed bit, further to increase transfer rate.
Referring to Fig. 2, the sampling point position of position 204 and other downward arrows set by CAN2.0B bits, in Fig. 2
In, SJW is identical with 2 width of CAN2.0B phase sections, and according to protocol requirement, width of the SJW less than phase section 2, ECAN's is every
Individual high-speed filling bit is with the definition with CAN2.0B identical sync sections, phase section 1 and phase section 2.206 and 211 is mode
1st, two " R " having under mode 2 and mode 3 arrive the conversion edge of " D ", hard along carrying out at the two when ECAN nodes are received
Synchronous, other synchronization rules are identical with CAN2.0B definition.The high-speed bit data filling mode of mode 1, mode 2 and mode 3 is protected
Having demonstrate,proved CAN2.0B nodes can carry out correct synchronization control, bit padding error checking during the transmission of ECAN frames, in ECAN
Node also carries out bit padding detection according to the rule and transfer rate of CAN2.0B when receiving ECAN frames, and for high-speed bit
Bit padding error detection is no longer carried out, adjustment is only synchronized.
Three kinds of fillings that high-speed bit data filling mode 1, mode 2 and mode 3 are only gived under the present invention program are shown
Example, it is other to be avoided that the filling of CAN2.0B nodes and the filling mode of timing error fall within this during ECAN frames send
Bright protection domain.
Again high-speed bit fill method is illustrated below：Frame format after filling should be able to be corrected in time due to high speed number
According to the mistake brought of uncertainty, in order to avoid there are many collections or leaks gathered data in error accumulation.Secondly, frame format after filling
Should ensure that CAN2.0B nodes discontinuously collect 6 identical values.Various padding schemes are obtained according to these two aspects factor, this
Invention be given as shown in Figure 2 three kind filling example, wherein SJW and SYN be respectively CAN2.0B nodes maximum jump width and
Sync section.
Mode 1：In CAN2.0B frame structures from after DLC fields, with the Bit Transmission Rate of CAN2.0B before CRC delimiters
Each R to D change after insert high-speed data（Dark filling part in Fig. 2）, this mode is equivalent to will be original
CAN2.0B frames divide into one group of every three bit, per group of bit value is R, a D, immediately following a high speed data transfer
Intermittently（Width is a CAN2.0B bit-time）；Before ECRC bits, with one R and D of CAN2.0B speed rates
Terminate；If the integral multiple of CAN2.0B transmitted bits number non-3 determined by DLC fields, if last group of only one of which
CAN2.0B bits, then the group transmit R, if the remaining two CAN2.0B bits of last group, the group is first transmitted R and transmits D again.
Mode 2：On the basis of mode 1 it is remaining after CAN2.0B frame sync segments and propagation segment 1 deduct SJW again when
Interior transmission high-speed bit, the false sync edge being likely to occur after making dark parts sampled point can be on the edge of next R to D
Corrected.
Mode 3：On the basis of mode 2 after the propagation segment during CAN2.0B transmission D deducts SJW in the remaining time
Transmission high-speed bit；In addition, it is contemplated that just there is the edge of R to the D of a determination per 3 bits, meeting CAN2.0B clock stables
On the premise of degree is required, can be by dark parts toward 2 internal diffusion of phase section 1 and phase section, further to increase transfer rate.
3 kinds of modes of the above were inserted the R and D, ECAN node of 1 standard CAN 2.0B frame before ECRC error bits and are existed
The edge carries out hard synchronization；Similarly, the edge of first R to D after DLC, ECAN nodes are also carried out hard synchronization.
Explanation in ECAN frames to DLC fields：The value for making DLC is, it is construed to transmit number in CAN2.0B nodes
According to byte number, it is allowed to value be 0～8, the value more than 8 is considered as 8.As ECAN frames are corresponded with CAN2.0B frames, because
This eachThe transmission data length of an ECAN frame has been corresponded to respectively.The transfer rate for making variable Rate part is
CAN2.0B transfer ratesTimes, it shows the ECAN frame data that can be transmitted during a CAN2.0B bit transfers gap
ForBit.
For the method based on high-speed bit filling is carried out to CAN2.0B data fields and CRC domains of the present invention,For
The DLC values that CAN2.0B and ECAN nodes can be recognized, it represents the transmission byte number of CAN2.0B frames in the frame, if passing at a high speed
The speed of defeated part is CAN2.0B speedTimes, then the bit number that ECAN can be transmitted in a frame is Fig. 1 and Fig. 2 institutes
The bit number of the dark filling part for showing.
For filling mode 1,The bits of user data number that corresponding ECAN frames are allowed is：
（For the CRC length of ECAN frames）, obtainWith ECAN frame data length（Bit number）Corresponding relation such as 1 institute of table
Show.In the application of ECAN frames, if the conveying length of the data length of actual transmissions and 1 defined of table is inconsistent, need to be
Application layer is first filled.
DLC under 1 filling mode 1 of table and HW frame valid data length respective value
| 1 | 5 | ||
| 2 | 6 | ||
| 3 | 7 | ||
| 4 | 8 |
For mode 2,The bits of user data number that corresponding ECAN frames are allowed is： （For the CRC length of ECAN frames,Synchronization for ECAN frames is redirected
Width）, obtainWith ECAN frame data length（Bit number）Corresponding relation（Here make）, as shown in table 2.
DLC under 2 filling mode 2 of table and HW frame valid data length respective value
| 1 | 5 | ||
| 2 | 6 | ||
| 3 | 7 | ||
| 4 | 8 |
For mode 3,The bits of user data number that corresponding ECAN frames are allowed is： （For the CRC length of ECAN frames,For the same of ECAN frames
Step redirects width）, obtainWith ECAN frame data length（Bit number）Corresponding relation（Here make）, as shown in table 3.
DLC under 3 filling mode 3 of table and HW frame valid data length respective value
| 1 | 5 | ||
| 2 | 6 | ||
| 3 | 7 | ||
| 4 | 8 |
Three kinds of fast bit filling modes are given in the present invention, but are not limited to these three filling modes when implementing,
Data field and CRC domains that can according to specific needs to CAN2.0B in implementing carry out allocating insertion pattern in advance, the pattern
Can using when set.
In order to realize coexisting in same network with CAN2.0B frames, the ECAN nodes realized based on the present invention first should can
Correctly recognize that the frame for receiving is CAN2.0B frames or ECAN frames, based on different applications, the ECAN nodes based on the present invention
The particular content of realization includes：
1）Support the reception of CAN2.0B all types frames；
2）If desired ECAN nodes are communicated with CAN2.0B nodes, then ECAN nodes need the Frame for realizing CAN2.0B to connect
Receive and send, defer to CAN2.0B agreements when communicating with CAN2.0B nodes；
3）If only supporting the communication of ECAN nodes, need to realize the reception monitoring of CAN2.0B Frames, ECAN can be distinguished
Whether frame and CAN2.0B frames, realize sending and receiving for ECAN frames given to this invention, and can be according to setting to CAN2.0B
The reception mistake of node is responded, and need not send CAN2.0B Frames.
Enhancement mode CAN protocol, i.e. ECAN protocol communications is adopted in the present invention between network node, ECAN agreements are right
CAN2.0B agreements redefine after agreement, the ECAN agreements cause using ECAN protocol communications node ratio adopt
There is the node of CAN2.0 protocol communications higher speed to realize the communication between node, while so that the employing ECAN agreements
The node of communication can coexist in same network with using the node of CAN2.0B protocol communications.Therefore, the present invention is existing in compatibility
On the premise of node using CAN2.0B protocol communications, the communication speed between the network node based on CAN agreement is improve
Rate.
The specific embodiment of the present invention is described in detail above in conjunction with accompanying drawing, but the present invention has been not restricted to
Embodiment is stated, in the case of the spirit and scope without departing from claims hereof, those skilled in the art can make
Go out various modifications or remodeling.
Claims (4)
1. a kind of CAN communication means of compatible CAN2.0B agreements, it is characterised in that using enhancement mode CAN protocol, i.e.,
ECAN protocol communications；Wherein, the ECAN agreements are the agreement after redefining to CAN2.0B agreements, and the ECAN agreements make
There must be higher speed to realize between node using the node ratio of ECAN protocol communications using the node of CAN2.0B protocol communications
Communication, while so that the node of the employing ECAN protocol communications can with coexisted in using the node of CAN2.0B protocol communications
Same network；
Wherein, the ECAN agreements are specifically configured to：
On the basis of CAN2.0B, retain its each field and redefine its long-range framing bit RTR, reserved bit R0 and R1
Distinguish CAN2.0B Frames and ECAN Frames, the definition of ECAN arbitrations by agreement domain and corresponding arbitration mechanism and CAN2.0B agreements
It is identical；High-speed bit data are filled in the data field corresponding to CAN2.0B agreements and CRC domains in ECAN agreements and realizes transmission speed
The lifting of rate, the filling of the high-speed bit data meet the bit padding rule of CAN2.0B agreements.
2. the CAN communication means of compatible CAN2.0B agreements according to claim 1, it is characterised in that the high speed
The filling of bit data adopts following first method：
Last " R " of one group of every 3 bit is completely used for transmitting high-speed bit, if the transfer rate of high-speed bit is
N times of CAN2.0B Bit Transmission Rates, then can be with the user data of transmission of n-bit per 3 CAN2.0B bits, and N is not less than 1
Integer.
3. the CAN communication means of compatible CAN2.0B agreements according to claim 2, it is characterised in that the high speed
The filling of bit data adopts following second method：
On the basis of first method, in addition to first group, the sync section of " R " bit of per group of beginning and phase section 1 deduct synchronization
The time for redirecting width S JW is used for transmitting high-speed bit.
4. the CAN communication means of compatible CAN2.0B agreements according to claim 3, it is characterised in that the high speed
The filling of bit data is in the following ways：
On the basis of second method, the phase section 1 for increasing per group " D " bit deducts the synchronous time use for redirecting width S JW
In transmission high-speed bit, further to increase transfer rate.
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| DE102015201019A1 (en) * | 2015-01-22 | 2016-07-28 | Wobben Properties Gmbh | Wind turbine and wind turbine bus system |
| CN105262655B (en) * | 2015-09-16 | 2018-08-07 | 复旦大学 | A kind of communication means with higher rate of compatible CAN2.0 buses |
| CN108833377A (en) * | 2018-05-30 | 2018-11-16 | 武汉高仕达电气有限公司 | A kind of improved CAN protocol data frame structure and data processing method |
| DE102018218720A1 (en) | 2018-10-31 | 2020-04-30 | Robert Bosch Gmbh | Subscriber station for a serial bus system and method for sending a message in a serial bus system |
| US11863320B2 (en) * | 2021-02-26 | 2024-01-02 | Dialog Semiconductor US Inc. | Communication media sharing among devices having dissimilar physical layer waveforms |
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