Transmission doesn't work when multiple fields are in the same byte

[Susurrus]

For example, my rudder status message has 3 fields, each 1 bit, packed into 1 byte. When it gets encoded into a transmission message, it ends up being 3 bytes. So the only thing that should need to change at this point is the function that generates bytes from the fields and values.

[Susurrus]

The following message is an example where this fails.

    <messageInfo name = "Set rudder status" id = "0x81" format = "standard" size = "1">
        <field
            name = "Calibrate"
            offset = "0"
            length = "1"
            signed = "no"
            type = "int"
        />
        <field
            name = "Reset"
            offset = "1"
            length = "1"
            signed = "no"
            type = "int"
        />
        <field
            name = "Enable"
            offset = "2"
            length = "1"
            signed = "no"
            type = "int"
        />
    </messageInfo>

[Susurrus]

• Endianness is not properly accounted for.
• Bit ordering within the bytes in the output sting is incorrect
• "Transmission error" occurs when sending NMEA2000 messages. Can also occur in other instances, make this error clearer.

[xela144]

The N2K error is actually from a different bug. See canport.py: https://github.com/xela144/CANaconda/blob/master/canport.py#L427-L429

One way of fixing this is to force the user to include an ID if he wants to broadcast.