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app-notes:can-tcpsockets-parsing [2018/02/05 12:12] preisig [Environment setup] |
app-notes:can-tcpsockets-parsing [2021/08/04 09:14] (current) |
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| ===== Environment setup ===== | ===== Environment setup ===== | ||
| - | {{:internal:can_environment.jpg}} | + | {{:can_environment.jpg}} |
| - | The above graphic illustrates how the test environment was built and what data gets transmitted. First to be able to simulate a CAN bus in a local environment PC1 runs [[https://www.peak-system.com/PCAN-FMS-Simulator-2.246.0.html|Peak Systems PCAN-FMS Simulator]] to generate CAN Frames based on the FMS Standard (supports FMS v 1.0 – 3.0). The generated frames are transmitted over Peak Systems PCAN-USB into a Netmodule Router (NB2800 used in the example). Two example scripts on the router work with the incoming CAN traffic and send it back out over TCP, where [[http://sockettest.sourceforge.net/|SocketTest]] runs an PC2 as a simple TCP server. SocketTest is a tool based on Java that allows testing of UDP and TCP client and server sockets. In our case SocketTest runs as a TCP server that is listening on Port 2000. | + | The above graphic illustrates how the test environment was setup and what data gets transmitted. First to be able to simulate a CAN bus in a local environment PC1 runs [[https://www.peak-system.com/PCAN-FMS-Simulator-2.246.0.html|Peak System PCAN-FMS Simulator]] to generate CAN Frames based on the FMS Standard (supports FMS v 1.0 – 3.0). The generated frames are transmitted over [[https://www.peak-system.com/PCAN-USB.199.0.html|Peak System PCAN-USB]] into a Netmodule Router (NB2800 used in this example). Two example scripts on the router work with the incoming CAN traffic and send it back out over TCP, where [[http://sockettest.sourceforge.net/|SocketTest]] runs an PC2 as a simple TCP server. SocketTest is a tool based on Java that allows testing of UDP and TCP client and server sockets. In our case SocketTest is configured as a TCP server that is listening on Port 2000. |
| ===== Setup the CAN Interface on the Router ===== | ===== Setup the CAN Interface on the Router ===== | ||
| To use the CAN Interface on the Router first you need to enable the CAN Interface with the correct Bitrate (250kBits used). | To use the CAN Interface on the Router first you need to enable the CAN Interface with the correct Bitrate (250kBits used). | ||
| - | {{:internal:netbox-can-setup.jpg?600|}} | + | {{:netbox-can-setup.jpg?600|}} |
| ===== Peaksystem PCAN-FMS Simulator ===== | ===== Peaksystem PCAN-FMS Simulator ===== | ||
| - | As mentioned in the introduction Peaksystems PCAN-FMS simluator is used to generate CAN Frames. The software is easy to use and allows a good starting point for local development. | + | As mentioned in the introduction Peaksystems PCAN-FMS simluator is used to generate CAN frames. The software is easy to use and allows a good starting point for local development. |
| {{:internal:peaksystem-pcan-fms-simulator.jpg}} | {{:internal:peaksystem-pcan-fms-simulator.jpg}} | ||
| ===== Incoming RAW CAN Frames on the Router: ===== | ===== Incoming RAW CAN Frames on the Router: ===== | ||
| - | The first and most simple test on the router was to use candump provided by the can-utils package to verify a working environment and to see the generated CAN traffic. Login to your router (over ssh or telnet) and run ''candump <can-interface>'' | + | The first and most simple test on the router is to use candump provided by the can-utils package to verify a working environment and to see the generated CAN traffic. Login to your router (over ssh or telnet) and run ''candump <can-interface>'' |
| By default, candump provides the following information: | By default, candump provides the following information: | ||
| - | {{:internal:candump.jpg}} | + | {{:candump.jpg}} |
| Interface, CAN Identifier, DLC and DATA | Interface, CAN Identifier, DLC and DATA | ||
| - | ===== Transmit CAN Frames over TCP Sockets (can-tcp-broadcast.are) ===== | + | ===== Forward CAN Frames over TCP Sockets (can-tcp-broadcast.are) ===== |
| - | To show a possible use of forwarding CAN Frames over Ethernet can-tcp-broadcast.are provides a TCP Client that broadcasts all incoming CAN Frames to one or several servers that can be passed as arguments. The SDK API already provides several functions to interact with CAN (see ftp://share.netmodule.com/router/public/system-software/latest/NB_SDK_API_Manual.pdf). | + | To show a possible use of forwarding CAN Frames over Ethernet can-tcp-broadcast.are provides a TCP client that broadcasts all incoming CAN Frames to one or several servers that can be passed as arguments. The SDK API already provides several functions to interact with CAN (see https://share.netmodule.com/public/system-software/latest/NB_SDK_API_Manual.pdf). |
| The function start_can() sets required attributes to the can interface and sets up a raw socket descriptor that is used in the main part of the script. Additionally filtering of CAN Identifiers is possible via nb_can_setfilter() to specify which CAN frames shall be filtered out and which shall be passed to upper layers. | The function start_can() sets required attributes to the can interface and sets up a raw socket descriptor that is used in the main part of the script. Additionally filtering of CAN Identifiers is possible via nb_can_setfilter() to specify which CAN frames shall be filtered out and which shall be passed to upper layers. | ||
| + | |||
| + | //Please be aware// that extended use of filtering or processing on the router itself may affect the overall processing power. An advice would be, to do data processing on a more powerful backend according to ones needs. | ||
| + | |||
| <code c from can-tcp-broadcast.are> | <code c from can-tcp-broadcast.are> | ||
| Line 60: | Line 63: | ||
| - | Within the main loop receiving CAN messages is done with nb_can_recvmsg() which returns CAN Frames as a msg struct. To examine the CAN ID of a message different bit operators are available. Since FMS uses the extended frame format CAN_EFF_MASK was applied. | + | Within the main loop receiving CAN messages is done with nb_can_recvmsg() which returns CAN frames as a msg struct. Since the CAN specification defines two different identifier formats (11-Bit Identifier - Base Frame Format & 29-Bit Identifier - Extended Frame Format) the SDK offers different bit operators to examine the CAN ID of a frame. The following bit operators are available for nb_can_recvmsg(): |
| + | |||
| + | * CAN_EFF_FLAG --- EFF/SFF is set in the MSB | ||
| + | * CAN_RTR_FLAG --- remote transmission request | ||
| + | * CAN_ERR_FLAG --- error frame | ||
| + | * CAN_SFF_MASK --- standard frame format (SFF) | ||
| + | * CAN_EFF_MASK --- extended frame format (EFF) | ||
| + | * CAN_ERR_MASK --- omit EFF , RTR , ERR flags | ||
| + | |||
| + | |||
| + | Since FMS uses the extended frame format the CAN_EFF_MASK bit operator was applied. | ||
| <code c from can-tcp-broadcast.are> | <code c from can-tcp-broadcast.are> | ||
| Line 81: | Line 94: | ||
| </code> | </code> | ||
| - | On the receiving end SocketTest listens on TCP port 2000 and displays the CAN Frames: | + | On the receiving end SocketTest listens on TCP port 2000 and displays the raw CAN frames: |
| - | {{:internal:sockettest-candump.jpg?600|}} | + | |
| - | + | ||
| - | This way data processing could be done on a more powerful backend according to ones needs. Please be sure to check the load of the router to assure normal operation of the device. | + | |
| + | {{:sockettest-candump.jpg?600|}} | ||
| ===== Simple CAN Frame parsing (simple-can-parser.are) ===== | ===== Simple CAN Frame parsing (simple-can-parser.are) ===== | ||
| An additional test was made to show a simple way of parsing CAN Frames. The example is based on checking for a specific PGN (parameter group number) and then get a SPN (supect parameter name) to display its value in human readable format which then gets logged in a file. | An additional test was made to show a simple way of parsing CAN Frames. The example is based on checking for a specific PGN (parameter group number) and then get a SPN (supect parameter name) to display its value in human readable format which then gets logged in a file. | ||
| Line 114: | Line 125: | ||
| </code> | </code> | ||
| - | ===== Resources & SDK Scripts ===== | + | ===== SDK Scripts ===== |
| - | The folllowing tools and ressources where used: | + | |
| - | + | ||
| - | * [[https://www.peak-system.com/PCAN-FMS-Simulator-2.246.0.html|Peaksystem PCAN-FMS-Simulator]] | + | |
| - | * [[https://www.peak-system.com/PCAN-USB.199.0.html|Peaksystem PCAN-USB-Adapter]] | + | |
| - | * [[https://sockettest.sourceforge.net/|SocketTest V3.0.0]] | + | |
| Below the used arena scripts (can-tcp-broadcast.are & simple-can-parser.are) are listed completly. | Below the used arena scripts (can-tcp-broadcast.are & simple-can-parser.are) are listed completly. | ||