CN207691836U - CAN bus terminal resistance coalignment - Google Patents
CAN bus terminal resistance coalignment Download PDFInfo
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- CN207691836U CN207691836U CN201721710943.9U CN201721710943U CN207691836U CN 207691836 U CN207691836 U CN 207691836U CN 201721710943 U CN201721710943 U CN 201721710943U CN 207691836 U CN207691836 U CN 207691836U
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Abstract
The disclosure is intended to provide a kind of CAN bus terminal resistance coalignment, leads to communication failure at least to solve the problems, such as that CAN bus terminal resistance is improper in the related technology.Disclosed CAN bus terminal resistance coalignment includes：There is multiple resistance and multidiameter option switch in the output end of CAN bus, the first end of multiple resistance is connected with multiple branches of the first end of multidiameter option switch respectively, it is connected with one end of CAN bus output end after the second end parallel connection of multiple resistance, the second end of multidiameter option switch is connected with the other end of CAN bus output end.The disclosure improves the stability of CAN network communication.
Description
Technical field
The utility model is related to data communication technology fields, in particular to a kind of CAN (Controller Area
Network, controller local area network) bus termination resistors match device.
Background technology
Signal amplitude in CAN bus is the guarantee of the correct recognition logic signal of receiving node energy.But in the reality of CAN bus
In the application of border, since signal has reflection in transmission process, if it exceeds CAN communication standard, gently then introduces common mode interference, lead
Communications failure is caused, it is heavy then lead to device failure.To ensure that CAN bus correctly communicates, the terminal in CAN communication network is needed respectively to add
The resistance value of one build-out resistor, the build-out resistor of terminal is connected up with real network and the impedance of the length, connection of connection has
Relationship, only chooses suitable build-out resistor, just can guarantee that CAN network communication is normal.Present inventor is in analysis failure
When mainboard, find to damage due to terminal resistance, the electromagnetic environment of complicated cabling and complexity can cause terminal resistance improper, cause
CAN communication failure, therefore propose the application.
Utility model content
Present disclose provides a kind of CAN bus terminal resistance coalignments, whole at least to solve CAN bus in the related technology
Hold resistance improper the problem of leading to communication failure.
According to one aspect of the disclosure, a kind of CAN bus terminal resistance coalignment is provided, including：In the CAN
There is the output end of bus multiple resistance and multidiameter option switch, the first end of the multiple resistance to be selected respectively with the multichannel
Select the first end of switch multiple branches be connected, after the second end parallel connection of the multiple resistance with one end phase of the output end
Even, the second end of the multidiameter option switch is connected with the other end of the output end.
Optionally, the CANH output ends and/or CANL output ends of CAN bus have the multiple resistance and the multichannel
Selecting switch.
Optionally, the resistance value of the multiple resistance is different.
Optionally, the form that the multiple resistance is arranged according to resistance value size order is multiple with the multidiameter option switch
Branch is connected.
Optionally, before the CAN bus powers on, the multidiameter option switch with according to resistance value size order arrangement
Resistance in an intermediate position is connected in the multiple resistance.
Optionally, the resistance value of the centrally located resistance is 120 ohm.
Optionally, it is in equal difference relationship between the resistance value of the multiple resistance.
Optionally, described device further includes AD (Analog-to-Digital, analog-to-digital conversion) device, the AD converter with
The output end of the CAN bus is connected.
Optionally, described device further includes：Controller, AD converter described in the input terminal of the controller is connected, described
The output end of controller is connected with the multidiameter option switch.
Optionally, described device further includes：Multiple CAN node devices and multiple CAN transceivers, the multiple CAN sections
Point device and multiple CAN transceivers are set between the CANH output ends and CANL output ends of the CAN bus.
The scheme that the embodiment of the present disclosure provides, the resistance of different resistance values is provided in CAN bus output end, according to detecting
CAN bus differential voltage control CAN bus output end switching access build-out resistor, to realize CAN bus terminal resistance
Auto-matching, improve the stability of CAN bus network.
Description of the drawings
Fig. 1 is a kind of flow chart of CAN bus terminal resistance matching process of the embodiment of the present application 1；
Fig. 2 is the schematic diagram of the table for indicating differential level value range in the embodiment of the present application 1；
Fig. 3 is the flow chart of another CAN bus terminal resistance matching process of the embodiment of the present application 1；
Fig. 4 is the block diagram of the CAN bus terminal resistance coalignment of the embodiment of the present application 1.
Specific implementation mode
Example embodiments are described in detail here, and the example is illustrated in the accompanying drawings.Following description is related to
When attached drawing, unless otherwise indicated, the same numbers in different drawings indicate the same or similar elements.Following exemplary embodiment
Described in embodiment do not represent all embodiments consistent with the utility model.On the contrary, they be only with such as
The example of the consistent device and method of some aspects be described in detail in the appended claims, the utility model.
Embodiment 1
A kind of CAN bus terminal resistance matching process is present embodiments provided, Fig. 1 is the flow chart of this method, such as Fig. 1 institutes
Show, this method comprises the following steps：
Step 101：Obtain the differential level of CAN bus；
In the present embodiment, the level magnitude that CANH and CANL can be obtained respectively by AD samplings, further according to CANH
The differential level CANdiff of CAN bus is calculated with the level magnitude of CANL.
Step 102：Judge differential level whether within preset range；
Since only receiving node could correct recognition logic letter in a certain range for the signal amplitude in CAN bus
Number, for example, the amplitude of the usually differential level CANdiff=(CANH-CANL) of CAN bus can just be identified as more than 0.9V
Dominant level, differential amplitude are identified as recessive level less than 0.5V, and Fig. 2 is the range of CAN level as defined in ISO11898,
In the present embodiment can according to fig. 2 shown in level range set in the present embodiment involved preset range.
Step 103：In the case where differential level is not within preset range, the output end of CAN bus is controlled from current
First build-out resistor of access switches to the second build-out resistor of access.
Wherein, the first build-out resistor is the build-out resistor that CAN bus output end accesses before handover, and second resistance is
CAN bus output end can select the arbitrary resistance of access by multinomial selecting switch.
In one case, the output end for controlling CAN bus switches to access from the first build-out resistor being currently accessed
The step of two build-out resistors may include：The output end of control CAN bus switches to pre- from the first build-out resistor being currently accessed
If multiple build-out resistors in the second build-out resistor, obtain the differential level of CAN bus output end again, and according to obtaining again
The differential level got judges whether to need the build-out resistor for switching output end (if the differential level got is not in default model
In enclosing, then the build-out resistor for switching CAN bus output end is needed, switching is otherwise not necessarily to), until the differential level got is pre-
Within the scope of if.
In another case, the output end for controlling CAN bus switches to access from the first build-out resistor being currently accessed
The step of second build-out resistor may include：The CANL and an output end in CANH for controlling CAN bus switch its access
Build-out resistor after, obtain CAN bus output end differential level, in the differential level got not within preset range
In the case of, control the build-out resistor that another output end in CAN bus switches its access.
In still another case, the output end for controlling CAN bus switches to access from the first build-out resistor being currently accessed
The step of second build-out resistor may include：
In the case where the differential level got is less than the lower numerical limit of preset range, the output end of CAN bus is controlled
The second build-out resistor of access is switched to from the first build-out resistor being currently accessed, in that case the resistance value of the second build-out resistor
More than the resistance value of the first build-out resistor；In the case where the differential level got is more than the upper limit value of preset range, CAN is controlled
The output end of bus is switched to from the first build-out resistor being currently accessed accesses the second build-out resistor, second in that case
Resistance value with resistance is less than the resistance value of the first build-out resistor.
Optionally, the CAN bus terminal resistance matching process of the present embodiment can also include：In the difference for obtaining CAN bus
Divide before level, detects the upper limit value and lower limiting value of the build-out resistor resistance value of CAN bus output end；Can be specifically to meet
The case where CAN bus basic communication need, gets off to detect the upper limit value and lower limit of the build-out resistor resistance value of CAN bus output end
Value is based on this, resistance value numerical value defined by the upper limit value and lower limiting value of build-out resistor resistance value of above-mentioned multiple preset resistances
In range.
Fig. 3 is the block diagram of the CAN bus terminal resistance coalignment of this implementation, total in another CAN to the present embodiment
Before line terminal resistance matching process illustrates, Fig. 3 is combined to match resistance value to the CAN bus terminal resistance of the present embodiment first
It is briefly described.
As shown in figure 3, in CAN bus communication network terminal there are a multidiameter option switch, which can
To select the resistance of different resistance values to access the output end of CAN bus.Exemplary, the resistance value of R3 shown in Fig. 3 can be defaulted as
120 ohm, the resistance value of other resistance can be chosen according to actual conditions, such as the relationship of resistance value can meet R1 between these resistance
<R2<R3<R4<R5.Can be measured respectively under conditions of ensureing CAN bus normal communication the upper limit value of terminal coupling resistance with
And lower limiting value so that R1, R5 value power in the numberical range defined by the upper limit value and lower limiting value measured
Afterwards, multidiameter option switch acquiescence chooses resistance R3, i.e., R3 is accessed to the output end of CAN bus.Come to this implementation below in conjunction with Fig. 4
The CAN bus terminal resistance matching process of example illustrates.
Fig. 4 is the flow chart of the present embodiment another kind CAN bus terminal resistance matching process, as shown in figure 4, this method packet
It includes：
In the initial state, multidiameter option switch selects R3 resistance, is selected in the build-out resistor to CAN bus terminal
When, after powering on initiation CAN communication, the level magnitude of CANH and CANL are taken respectively by AD samplings, according to CANH and CANL
Level magnitude calculate the differential level CANdiff of CAN bus.If the differential level being calculated is within a preset range,
It is then not necessarily to adjust the resistance value of CAN bus output end access；If calculated differential level CANdiff is not in preset range
It is interior, if differential level amplitude is less than normal, then it is assumed that the resistance R3 of current CAN bus selection is less than normal or resistance R3 is damaged, this
When control multidiameter option switch select a resistance else toward the direction of R5, until differential electrical level values within a preset range.It is calculating
Differential level CANdiff not within preset range in the case of, think that CAN bus is currently selected if differential level is bigger than normal
The resistance R3 selected is bigger than normal, controls multidiameter option switch at this time and selects a resistance else toward the direction of R1, until the value of differential level exists
Within preset range.
The CAN bus terminal resistance matching process of the present embodiment can solve in CAN bus communication network due to terminal electricity
Resistance mismatches communication caused by CAN nodes None- identified caused by (terminal resistance is bigger than normal or less than normal) and terminal resistance damage
Abnormal problem improves the stability of CAN bus network.
Embodiment 2
A kind of CAN bus terminal resistance coalignment is present embodiments provided, Fig. 3 is an illustrative frame of the device
Figure, as shown in figure 3, the device includes following component part：
In the output end of CAN bus there is multiple resistance and multidiameter option switch, the first end of multiple resistance to distinguish
Be connected with multiple branches of the first end of multidiameter option switch, after the second end parallel connection of multiple resistance with CAN bus output end
One end be connected, the second end of multidiameter option switch is connected with the other end of CAN bus output end.With R1, R2, R3, R4 in Fig. 3
And R5 carries out example to multiple resistance in the present embodiment.
In the present embodiment, there are the CANH output ends and/or CANL output ends of CAN bus multiple resistance and multichannel to select
Switch is selected, Fig. 3 shows that the ends CANH and CANL all have a kind of situation of multidiameter option switch and multiple resistance.
In the present embodiment, the resistance value of multiple resistance is different, and in one case, multiple resistance is suitable according to resistance value size
The form of sequence arrangement is connected with multiple branches of multidiameter option switch successively, i.e. between multiple resistances shown in Fig. 3
Relationship can be expressed as：R1<R2<R3<R4<R5.
In the present embodiment, before CAN bus powers on, multidiameter option switch with according to resistance value size order arrangement it is more
Resistance in an intermediate position is connected in a resistance, as shown in figure 3, multidiameter option switch acquiescence is connected with resistance R3.It is exemplary,
R3 resistance values are defaulted as 120 ohm.
In the present embodiment, can be in equal difference relationship between the resistance value of multiple resistance, for example, R1~R5 can be 80 successively
Ohm, 100 ohm, 120 ohm, 140 ohm and 160 ohm.
Optionally, the CAN bus terminal resistance coalignment of the present embodiment can also be including AD converter (in Fig. 3 temporarily not
Show), which is connected with the output end of CAN bus, for CAN bus carry out AD samplings, obtain CANH and
The level magnitude of CANL.
Optionally, the CAN bus terminal resistance coalignment of the present embodiment can also include controller, the controller it is defeated
Enter to hold AD converter to be connected, the output end of controller is connected with multidiameter option switch, which can sample according to AD and obtain
CANH and the level magnitude control multidiameter option switch of CANL access the resistance of different resistance values.
As shown in figure 3, the CAN bus terminal resistance coalignment of the present embodiment further includes：Multiple CAN node devices and
Multiple CAN transceivers, multiple CAN node devices and multiple CAN transceivers be set to CAN bus CANH output ends and
Between CANL output ends.
The CAN bus terminal resistance matching process of the present embodiment can solve in CAN bus communication network due to terminal electricity
Resistance mismatches communication caused by CAN nodes None- identified caused by (terminal resistance is bigger than normal or less than normal) and terminal resistance damage
Abnormal problem improves the stability of CAN bus network.
Those skilled in the art will readily occur to this practicality after considering specification and putting into practice utility model disclosed herein
Novel other embodiments.This application is intended to cover any variations, uses, or adaptations of the utility model, these
Variations, uses, or adaptations follow the general principle of the utility model and include undocumented skill of the utility model
Common knowledge in art field or conventional techniques.The description and examples are only to be considered as illustrative, the utility model
True scope and spirit are indicated by the following claims.
It should be understood that the utility model is not limited to the accurate knot for being described above and being shown in the accompanying drawings
Structure, and various modifications and changes may be made without departing from the scope thereof.The scope of the utility model is only wanted by appended right
It asks to limit.
Claims (10)
1. a kind of CAN bus terminal resistance coalignment, which is characterized in that including：
There is multiple resistance and multidiameter option switch, the first end point of the multiple resistance in the output end of the CAN bus
Be not connected with multiple branches of the first end of the multidiameter option switch, after the second end parallel connection of the multiple resistance with it is described defeated
One end of outlet is connected, and the second end of the multidiameter option switch is connected with the other end of the output end.
2. the apparatus according to claim 1, which is characterized in that the CANH output ends and/or CANL of the CAN bus export
End has the multiple resistance and the multidiameter option switch.
3. the apparatus according to claim 1, which is characterized in that the resistance value of the multiple resistance is different.
4. device according to claim 3, which is characterized in that the shape that the multiple resistance is arranged according to resistance value size order
Formula and multiple branches of the multidiameter option switch are sequentially connected.
5. device according to claim 3, which is characterized in that before the CAN bus powers on, the multi-path choice is opened
Pass is connected with resistance in an intermediate position in the multiple resistance arranged according to resistance value size order.
6. device according to claim 5, which is characterized in that the resistance value of the centrally located resistance is 120 Europe
Nurse.
7. device according to claim 3, which is characterized in that be in equal difference relationship between the resistance value of the multiple resistance.
8. the apparatus according to claim 1, which is characterized in that described device further includes：
Analog/digital AD converter, the AD converter are connected with the output end of the CAN bus.
9. device according to claim 8, which is characterized in that described device further includes：
Controller, AD converter described in the input terminal of the controller are connected, and the output end of the controller is selected with the multichannel
Switch is selected to be connected.
10. according to the device described in claim 1 to 9 any one, which is characterized in that described device further includes：
Multiple CAN node devices and multiple CAN transceivers, the multiple CAN node devices and the setting of multiple CAN transceivers
Between the CANH output ends and CANL output ends of the CAN bus.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721710943.9U CN207691836U (en) | 2017-12-06 | 2017-12-06 | CAN bus terminal resistance coalignment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201721710943.9U CN207691836U (en) | 2017-12-06 | 2017-12-06 | CAN bus terminal resistance coalignment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN207691836U true CN207691836U (en) | 2018-08-03 |
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ID=62996632
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201721710943.9U Active CN207691836U (en) | 2017-12-06 | 2017-12-06 | CAN bus terminal resistance coalignment |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN207691836U (en) |
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2017
- 2017-12-06 CN CN201721710943.9U patent/CN207691836U/en active Active
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