Network

The Network object is used for managing the CAN network & stack. It holds CANopen Nodes which can be of two types : Either a LocalNode, which represents a real CANopen CiA 301 compliant node or a RemoteNode which is the local representation of a remote CANopen node on the CAN bus used for master control.

The network already embeds some CANopen functionalities such as : - SDO Client - NMT Master

SDO client can be used by running :

// Read node id 0x10, index 0x2000, subindex 0x0 inside buffer
// No decoding is done
nbRead,err := network.ReadRaw(0x10,0x2000,0,buffer)

// Write node id 0x10, index 0x2000, subindex 0x0
// value can be any CANopen standard type
value := uint16(600)
nbRead,err := network.WriteRaw(0x10,0x2000,0,value,false)

NMT Master :

// RESET all nodes on the network
network.Command(0,nmt.CommandResetNode)

// RESET node id 0x10
network.Command(0x10,nmt.CommandResetNode)

A network scan of all the available devices can be performed. This will send an SDO request to all the nodes and wait for a reply. This expects the identity object to exist on the remote node (in conformance with CiA standard).

// Scan for existing nodes on the bus, if no response is received after 1 second
// It is considered as non existent
timeoutMs := 1000
devices,err := network.Scan(1000)

Remote node

A remote node can be used to control another node on the CAN bus. To create a remote node, several options are possible : - By providing an object dictionary (either EDS file, or ObjectDictionary object) - By downloading the EDS from the remote node (SDO upload). In that case, two formats are currently supported by default : ASCII and ZIP.

// Add a remote node, with id 6 and load the object dictionary from given file
node := network.AddRemoteNode(6, "/path/to/object_dictionary.eds")

// First download EDS file. An optional callback can be provided for manufacturer specific parsing
// Then add remote node
odict,_ := network.ReadEDS(6, nil)
node := network.AddRemoteNode(6, odict)

Local node

A local node is a fully functional CANopen node as specified by CiA 301 standard. A node can be created with the following commands:

// Create & start a local node with the default OD in the libraray
node,err := network.CreateLocalNode(0x10,od.Default())

Custom OD parsing

The network can be configured to use a different OD parser when creating local nodes.

// Change default OD parser
network.SetParsev2(od.ParserV2)

Custom node processing

Nodes can also be added to network and controlled locally with a NodeProcessor. e.g.

// Create a local node
node, err := network.NewLocalNode(
        network.BusManager,
        slog.Default(),
        odNode, // OD object ==> Should be created
        nil, // Use definition from OD
        nil, // Use definition from OD
        nodeId,
        nmt.StartupToOperational,
        500,
        sdo.DefaultClientTimeout,
        sdo.DefaultServerTimeout,
        true,
        nil,
    )


// Add a custom node to network and control it independently
proc,err := network.AddNode(node)

// Start node processing
err = proc.Start(context.Background())

More information on local nodes here