Csdrhrt

I have been working on a project and I ran into a port command problem, but before I ask the question I need to explain the set up, my goal, and my problem.

Set Up:

So I have a Raspberry Pi 3 B+ connected to the CANable CAN interface via USB. The Pi has the Raspian software installed, and I use the desktop to manage files and use the command line to execute programs, and communicate with the CAN interface. I also installed can-utils and python-can by using the commands:

apt-get install can-utils

pip install python-can

The CANable has the Candlelight software installed, which allows me to use the can-utils commands to communicate with it.

Goal:

I need to be able to playback(send) CAN messages stored in my .asc files from my Pi through my CANable CAN interface to be received by another CAN node.

Problem:

So I was able to set up the can0 port by pluggin the CANable with USB and then using this command:

sudo ip link set can0 up type can bitrate 1000000 restart-ms 100;

I wanted to test can0 so I opened two command prompts. One to send CAN messages and the other one to monitor the received messages. To monitor I used:

candump -e any,0:0,#FFFFFFFF

and to send random messages to can0:

cangen can0

These are the results:

Sending Messages Results

Monitoring the Mesages

Also if I open the status of can0 by using "ip -det -stats link show can0" It shows that it is in the "Error Passive" mode and that 10 packets have been dropped in TX. So it looks like there is an acknowledgment problem as well as a TX buffer space problem. I assumed that it needs the message to be acknowledged and if it is not then the buffer gets full and then the connection drops. What I did to get around this was I activated the loopback function by:

sudo ifconfig can0 down;

sudo ip link set can0 up type can bitrate 1000000 restart-ms 100 loopback on;

When I do this there are no errors and I am able to see the messages using candump, but the problem is that each message line is echoed back to can0 and I see two of the same lines repeated in candump. Also, I can't find a way to reset can0 to clear the buffer other than disconnecting the CANable or shutting down the Pi. I tried:

sudo ip link set can0 type can restart;

I get: "RTNETLINK answers: Invalid argument"

I do not get these problems if I create and use a virtual CAN port (vcan0) instead of using an actual physical CAN node such as the CANable (can0).

Questions

Is there a way to pass the acknowledgment problem without the use of the loopback function so I can send the messages that I want without echo? (Like maybe using the virtual CAN node to acknowledge the messages)

If I hook up another CANable to my CANable will the messages acknowledge?

Why doesn't can0 reset even though I have the "restart-ms 100" in the command?

Why can't I reset the buffer or the information about packets by using the restart command?

Any help would be appreciated.