[Feature Request]: Java Canopen - Sending NMT Commands

[freelancer1845]

What would you like to happen?

Hey,

currently it is not possible to send NMT commands to nodes.
Some nodes do not automatically transition into "Operational" state.
Subscribing to NMT messages is already implemented. The same style would also work for sending NMT commands.

My current workaround is something like this (if anyone has the same problem):

    public static void sendNmtCommand(PlcConnection connection, int nodeId, NmtCommands command) {
        if (connection instanceof DefaultNettyPlcConnection defaultConnection) {
            var channel = (SocketCANChannel) defaultConnection.getChannel();
            ByteBuf frame = Unpooled.buffer(16);
            frame.retain();
            frame.writeIntLE(0x000); // can_id (11-bit ID in lower bits)
            frame.writeByte(2); // can_dlc
            frame.writeByte(0).writeByte(0).writeByte(0); // padding
            frame.writeBytes(new byte[] {
                    command.value, (byte) nodeId,
                    0, 0, 0, 0, 0, 0 // data[8] total
            });
            channel.writeAndFlush(frame);
        } else {
            throw new IllegalStateException("Expected DefaultNettyPlcConnection from CanOpen connection");
        }

Programming Languages

• plc4j
• plc4go
• plc4c
• plc4net

Protocols

• AB-Ethernet
• ADS /AMS
• BACnet/IP
• CANopen
• DeltaV
• DF1
• EtherNet/IP
• Firmata
• KNXnet/IP
• Modbus
• OPC-UA
• S7