CANbus Handshake?

PAC Project
1

Currently, using one CANbus module, we are trying to do a handshake to a system control unit. Only way we can see to do this with your design is to run a loop where we:
turn off canbus reception,
turn on transmission,
transmit step one of the handshake,
turn off transmission,
turn on reception,
wait for ack,
if no ack, rerun loop.

We are doing monitoring of the CANbus for diagnostic reasons all the time, so when we turn off the reciever, we lose messages.
Is there a better way to do this? are we stuck with this due to comm protocol? Do we need to run 2 canbus modules, one just for transmitting? and on that note, why dont you guys have 2 transievers on that CAN2b module? there sure is room for it.

2

Looking for some help on CAN2B module
I Cannot Get connection, I have a can simulator but nothing is being read in
Any Help is more than i have now

3

I worked on creating a CAN Analyzer back in 2015. I can’t even remember the state I left it in, but it did work at one time. I have attached an archive zip file, which loads into PAC Control 10.2 successfully. No guarantees on this strategy - it was too long ago. My purpose was to try out the subroutines and also create an analyzer that worked with PAC Display as the user interface (also attached). If I recall, I had trouble with it dropping messages when I switched to transmit.
Maybe this will help.
CanAnalyzer.Archive.D09172015.T165036.zip (42.2 KB)
CanAnalyzer.UUI_Archive_2015-09-17_16-51-56.zip (14.6 KB)

4

I will take a look much appreciated

5

Excellent tool! Easy to understand also, I am receiving information, the problem with the can receive tool kit is the mask that is hard coded ,

I appreciate the help and now have to parse the data but it’s easy compared to scratching my head wondering why I do not see anything

6

Hi D_Engsberg,

I am working on a CAN application in PAC Control using SNAP-SCM-CAN2B.
I have decided to give your analyzer a try since I am basically starting from scratch.
The device I want to communicate with is a microwave generator.
The device uses CAN protocol (CAN layer 2 with 11 bit identifier).

I am hoping that I will be able to receive data with your chart and then figure out how to parse the data I receive.

7

I happen to be starting another project with the SNAP-SCM-CAN2B right now. The Analyzer was meant to be very generic.
The new project is a connected to a battery management system that sends 4 messages, and to a customized display that I need to send 1 message to. I will have to take a look at how I did the analyzer, but I might take another completely different approach since I know exactly what the incoming messages look like.
You can open the communications channel to the Can module almost as if it was a serial port. Characters are waiting in the receive buffer to be read out and tested parsed.
I should know more in a week or so. I will keep you posted if I decide to use a different method.

8

Thanks for your reply! That is a coincidence, because the MW generator I want to communicate with is sending 4 “telegrams” at once. I think they mean 4 data frames with 8 bytes and 8 bits per byte.

I will need to be able to send two different sets of telegrams , basically switching the unit on with some user defined set points and off again.

Are the opto22 receive and send/receive subroutines going to pick up multiple frames without changing the subroutine in some way?

I think your parse/receive messages block would only parse one frame, is that right?

I haven’t been able to test it as I am still building my control panel, but I might try to read messages with Pcan or Peak to get started.