CODEWITHSUNDEEP
can-bus
Tod
Tod

Reputation: 8242

Does a CAN bus device need to be kick started to start sending messages?

I am a complete CAN bus newbie. I'm hoping someone with CAN experience can point me in the right direction. I was given a Vector VN1610 USB to CAN adapter and a Continental ARS-308 radar sensor. The goal is to read some velocity and distance information from the sensor. Right now I am just trying to see any data but all I get are messages with an id of 0 or 0x80000000. The data payloads all report as 8 bytes of 0.

What Works

I have been able to use the sample .NET code provided and set up the VN1610. The ARS-308 has a single CAN channel so in the Vector Hardware Config for my application I just map "CAN 1" to VN16101 Channel 1. (I leave CAN 2 unassigned) I then assume I use that one channel for both transmit and receive. The code reports that the channel sets up an activates and no errors are reported. I then have a thread looking for incoming messages. If I don't debug out the two IDs mentioned above I can actually process all of them and then I get XL_ERR_QUEUE_IS_EMPTY messages. So it looks like its all working, I'm just not getting any real data.

What Doesn't

I would think a slew of data messages in the 0x200 - 0x702 range would be coming in for the Continental ARS device. Now I'm more used to ethernet type protocols where I would send a command and then read a response. None of my docs talk about how CAN works so I am ASSUMING that in CAN the device just sends data. I certainly can't find any commands that tell the device to send me the particular msg ID I'm interested in. Am I missing some basic CAN configuration step that informs the device it should start sending data? Any suggestions at all would be appreciated.
If it matters I'm writing in VS2013, .NET on a Win 7 64 Ultimate machine.

Upvotes: 1

Views: 1112

Answers (1)

Tod
Tod

Reputation: 8242

The answer is No. It turns out that CAN devices will indeed just start streaming out messages when you turn them on (well at least this one does). The messages with ids of 0x0 and 0x8000000 are bogus. Even with the radar sensor turned off I continued to see those messages.

It turns out I had a hardware problem. The CAN bus requires a 120 Ohm resistor which was installed. The problem was when the shell was put back on the cable the resistor got cracked. Once we repaired this, everything started working as expected.

Upvotes: 2

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