All Questions
Tagged with can termination
43
questions
0
votes
3
answers
151
views
Add or remove 120 Ohm from the CAN circuit using Microcontroller
I want to design hardware circuit using microcontroller for CAN communication. One suggestion i require is i want to add 120 Ohm or remove it based on software configuration. I want to close the ...
- 437
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votes
1
answer
60
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CAN BUS Termination resistor sizing
I am using ISO1042 CAN Transceiver to establish communication between my board micro-controller with other board controller separated by 0.5m distance. I am using standard 120 ohm termination ...
1
vote
3
answers
140
views
GPIO controlled CAN bus termination technique
I have tried to design a circuit for controlling the CAN bus 120 Ohms termination resistance by using a 3.3V GPIO from a STM32 MCU.
In the SSR datasheet, it specifies that the LED voltage should ...
- 79
1
vote
1
answer
41
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Is a CAN bus device necessary at the end of the terminated network line?
I am designing a CAN bus network with three devices near one end and one device at the other end about 8' away. As long as I retain the terminator at the far end, is a device at the far end required ...
- 11
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0
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89
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CAN FD termination with plugged in modules
Is it possible to use CAN FD in scenario in which there is single main device and additional modules are plugged or hot plugged into each another?
MAIN->MOD1->MOD2->MODn
The main device will ...
- 137
4
votes
0
answers
152
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Is there an antenna problem with CAN Bus selectable split termination header pin?
I am trying to implement a jumper-selectable CAN Bus termination with a SPLIT configuration, as shown in this Analog Devices example:
https://www.analog.com/media/en/technical-documentation/user-...
- 355
1
vote
2
answers
2k
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CAN Bus termination resistor in only 2 device connection
A termination resistor in CAN ( .. or other differential pair communication like RS485 ) is necessary to absorb reflection. The value is related to wire length, electrical frequency, baud rate. It ...
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7
votes
2
answers
309
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Novel CAN bus design - needs criticism
I'm designing a CAN bus interface for a PCB I'm working on. CAN and high speed/long distances are new to me, so I have a list of concerns about my design ideas, and I would appreciate someone with ...
- 89
0
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2
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992
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Tap into CAN bus
I'm thinking about tapping into an existing CAN bus. I'm going to attach in a middle point, and I don't want to introduce any issue in the original bus.
In order not to disturb the original bus with ...
- 1,240
0
votes
0
answers
412
views
CAN bus termination resistor
I'm trying to design a CAN device where the user can select which device is the beginning/end device and activate the 120 ohm resistor accordingly. I've seen some examples using a switch, but I'm ...
- 201
1
vote
3
answers
514
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Can a node on a terminated end of a CAN bus self-identify that it is the final node?
Using the example below, is there any way for Node1 or Node3 to be able to recognize that they are the final nodes on the CAN bus? I want to allow my device to automatically enable a 120Ohm ...
0
votes
1
answer
885
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CAN physical layer fault conditions Short circuit to battery on CANH and CANL lines analysis
In case of short circuit to battery on CANH, would the current flow as analysed below ? This is in the case of CAN transceiver TJA1042T and I got the internal block of the transciever by NXP.
Data ...
- 87
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votes
2
answers
1k
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Star configuration using CAN Bus, I2C or RS485
I need to create a sensor network, with a central node receiving data from +10 different nodes, each one +20meters from the central node. So basically I need to create a star configuration, with a ...
0
votes
1
answer
283
views
Considerations for CAN termination resistor location
I'm looking to incorporate a switchable 120Ω termination resistor (using a photo MOSFET) into a CAN design. Are there any issues with locating the 120Ω resistor at the CAN transceiver versus at the ...
- 183
0
votes
2
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2k
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CAN Stub node termination in a network - 9.28k resistor
In a CAN network, the ends of the network has to be terminated with 120 ohm - I understand this. The middle node in the below diagram is the stub node and it does not have to be terminated, my stub ...
- 87
3
votes
2
answers
4k
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CAN Split Termination Capacitor Calculation
I'm trying to use the split termination on a CAN bus, but I'm a bit confused about the calculation for the split termination capacitor. It is described in Figure 10 in the Texas Instruments app note ...
- 1,197
1
vote
2
answers
2k
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Selectable CAN bus split termination
I am designing a CAN device where the user may switch between it being the end device and thus with terminators or vice versa.
Now, there is no need to drive it digitally using MCU, I would actually ...
- 38
1
vote
1
answer
308
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Does the standard termination of 120 ohm really suppress reflections in recessive state in CAN?
Suppose we have a multi-node CAN network with the ends of transmission line terminated with the standard 120 ohm. When the recessive state is on the transmission line, the voltage on both CAN_H and ...
0
votes
1
answer
837
views
CAN BUS Termination Resistors For CAN Logger Device
I am making a CAN logger device that will be connected to the vehicle OBD port. Since the CAN bus inside the vehicle is already terminated, do I need to terminate the BUS lines on my device end, right ...
- 383
1
vote
2
answers
2k
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Should I remove the termination resistor from the CAN Bus transceiver module?
I develop a CAN-BUS receiver (logger) with an ESP32 and CAN-BUS transceiver.
The CAN-BUS transceiver modules which I found and bought have both 120 Ohm termination resistors. But the CAN-BUS to which ...
- 293
2
votes
3
answers
998
views
CAN Physical Layer With Different Characteristic Impedance
The company I have been working for, which is designing a new control system for forestry equipment, has encountered a number of problems with regards to the CAN bus it is using for communication. I ...
- 21
0
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1
answer
140
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Do I need to measure impedance before every CAN termination?
Background: I need to set up a CAN bus between different components of an electric UAV (battery management system, motor inverter, autopilot, etc.). My avionics/networking experience up to now ...
- 456
3
votes
1
answer
1k
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How would I place CAN termination resistors in a 3 ended configuration?
I have a project for which I have one central circuit board which has a can node on it, this central circuit board has three connectors on each of which a node could or could not be plugged in with a ...
- 127
3
votes
1
answer
6k
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The CAN bus in this vehicle has only one 120 ohm termination resistance. What problems would this provoke?
This vehicle that I've started co-developing is designed with only a 120 termination resistor on the CAN bus. Obviously there should be two of those resistors on two ends of the bus. I will be making ...
- 133
2
votes
1
answer
3k
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Common mode choke parameters CAN circuitry - split termination concept
I am trying to the understand the important parameters of a common mode choke that will be placed at the CANL and CANH lines of a transceiver.
First parameter: Impedance as function of frequency - I'...
- 41
2
votes
3
answers
3k
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How far can a terminating resistor be from the literal end of a CAN bus?
I'm wondering if anyone knows if there is an upper limit for the distance a terminating resistor can be from the literal end of the CAN bus or where the last node is.
We have an HMI that is connected ...
- 53
1
vote
0
answers
570
views
How does the data rate of a CAN bus affect the value of the capacitor used in a split termination scheme?
I'm helping to redesign the CAN bus of an electric car, and we're interested in achieving higher data rates of up to 8 Mbit/s. We have a transceiver selected, a CMC to reduce inductively coupled ...
- 11
2
votes
1
answer
489
views
Terminator in Raspberry Pi CAN-shield
I am planning to connect (at least) two Raspberry Pi + PiCAN2 shields via CAN.
I think I understand the concept of a daisy-chained multidrop CAN line, but what about using the 120 ohm resistors for ...
- 180
1
vote
1
answer
240
views
CAN bus cable-termination mismatch
I am trying to change the CAN cables alone to Cat 6 cables (which has 100 ohm characteristic impedance). The existing cable has 120 ohm impedance. By making this change to Cat 6 cables, I am ...
- 11
1
vote
1
answer
238
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Check of my first Eagle boards
I am attaching two boards I have just designed in Eagle and would appreciate if any expert around here willing to take a quick look would flag any obvious errors in the design.
There is one board ...
- 23
7
votes
1
answer
9k
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How many (m)W should 120 ohm CAN bus terminators have?
When I started with Arduino I bought a set of 600 resistors (30 times 20 values). However, I found out 120 ohm needed for CAN bus is not among them.
So I need to buy 120 ohm resistors (I don't want ...
- 14k
0
votes
3
answers
113
views
Under which circumstances would CAN communication still work if there is no bus termination?
The bus termination is needed to prevent reflections. Does this mean that it may be possible to get a working communication with a low data rate, since then reflections might not interfere with the ...
- 103
7
votes
4
answers
4k
views
Does it matter which 2 nodes on a CAN bus you terminate?
I know you need to terminate the 'ends' on a high speed CAN bus but what if you know nothing about the topology of the network or where the bus will go. For my application i have designed a data ...
- 155
1
vote
1
answer
6k
views
Proper CAN bus termination
I've been struggling with getting CAN bus transmission to work properly. I'm driving the setup with a Parallax Propeller board and the specifics are in another post, but I have a more specific ...
- 273
3
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1
answer
2k
views
How and why is impedence matching done for a CAN bus?
What is that termination problem? Could anyone explain in detail?
- 33
2
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1
answer
1k
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CAN Bus and its Termination Resistor [duplicate]
I have a very basic question about the termination resistor of the CAN Bus. I know that a termination resistor is needed in order to avoid unwanted reflections. Since the characteristic impedance of a ...
- 79
7
votes
2
answers
3k
views
Will this selectable CAN BUS termination circuit work?
I'm trying to find a simple way of having software selectable termination on the CAN bus of a device I am making.
I think a Solid state relay is the best bet so I have come up with the following ...
- 896
3
votes
1
answer
2k
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Implementing CAN bus software termination
I noticed that a lot of CAN new test equipment allow you to enable/disable the termination via software. Is there an new transceiver in the market or an accepted way to implement this??
- 31
2
votes
1
answer
516
views
Using different termination types on CAN bus
Is it possible to terminate one end of a CAN bus using Standard termination (single 120 ohm resistor across CANH and CANL) and the other end using Split termination (two 60 ohm in series with a ...
- 21
2
votes
1
answer
1k
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CAN network resistor termination [duplicate]
My question is about the resistor for termination in a CAN network.
From an electrical perspective why should we add this resistor (commonly 120 Ohm) between the CAN_H and CAN_L?
Thanks in advance.
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votes
2
answers
6k
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CAN Transmission and termination resistors
I have been trying to set up a CAN network using PIC18F25K80 microcontrollers and an MCP2551 to communicate between them. Can I use two simple wires as a CAN bus by just connecting the CANL, CANH of ...
5
votes
1
answer
1k
views
Coax cable with CAN bus
I got some Microchip CAN transceivers and some Stellaris Launchpads from TI. I would like to learn how CAN works. It looks very nice for what I want to do (one controller per room, controls lights, ...
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41
votes
4
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175k
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Why does the CAN bus use a 120 ohm resistor as the terminating resistor and not any other value?
I know the reasons for using terminating resistors on a CAN bus and how important it is.
But why 120 ohm? How did this value come up? Is there any specific reason to use 120 ohm?
- 3,275