Usage

OPC UA server

Upon installation the commandline tool DCSControllerServer is created. In most cases there should be almost no configuration neccessary as it does not even have any positional arguments:

usage: DCSControllerServer [-h] [-E ENDPOINT] [-e EDSFILE] [-x XMLFILE]
                           [-K | -A] [-C CHANNEL] [-i IPADDRESS] [-b BITRATE]
                           [-c {NOTSET,WARNING,INFO,VERBOSE,CRITICAL,DEBUG,SUCCESS,NOTICE,ERROR,SPAM}]
                           [-f {NOTSET,WARNING,INFO,VERBOSE,CRITICAL,DEBUG,SUCCESS,NOTICE,ERROR,SPAM}]
                           [-d LOGDIR] [-v]

CAN interfaces:

-A, --anagate: Use AnaGate CAN Ethernet interface
-K, --kvaser: Use Kvaser CAN interface

OPC UA server configuration:

-E ENDPOINT, --endpoint ENDPOINT: Endpoint of the OPCUA server (default: opc.tcp://localhost:4840/)
-e EDSFILE, --edsfile EDSFILE: File path of Electronic Data Sheet (EDS) (default: /path/to/source/CANControllerForPSPPv1.eds)
-x XMLFILE, --xmlfile XMLFILE: File path of OPCUA XML design file (default: /path/to/source/dcscontrollerdesign.xml)

CAN settings:

-C CHANNEL, --channel CHANNEL: Number of CAN channel to use (default: 0)
-i IPADDRESS, --ipaddress IPADDRESS: IP address of the AnaGate Ethernet CAN interface (default: 192.168.1.254)
-b BITRATE, --bitrate BITRATE: CAN bitrate as integer in bit/s (default: 125000)

Logging settings:

-c LEVEL, --console_loglevel LEVEL: Level of console logging (default: NOTICE)
-f LEVEL, --file_loglevel LEVEL: Level of file logging (default: INFO)
-d LOGDIR, --logdir LOGDIR: Directory where log files should be stored (default: /path/to/source/log/)

Possible logging levels are:

Miscellaneous:

-h, --help: Show help message and exit
-v, --version: Show program’s version string and exit

AnaGate CAN interfaces

It is very easy to connect to AnaGate CAN interfaces using the Channel class. Incoming CAN messages can be received via the analib.channel.Channel.getMessage() method or by defining a callback function like analib.channel.cbFunc().

Using callback functions

It is quite easy to define a callback function for incoming CAN messages. Once defined it can be easily applied using the the setCallback() method. To deactivate a callback function it is neccessary to create a NULL pointer with the cast() function. This is done automatically when the Channel is closed. For documentation of the arguments please refer to analib.channel.cbFunc(). An example code is given below:

import analib
import ctypes as ct

def cbFunc(cobid, data, dlc, flag, handle):
    # Convert ct.LP_c_char to bytes object
    data = ct.string_at(data, dlc)
    print('Calling callback function with the following arguments:')
    print(f'    COBID: {cobid:03X}; Data: {data[:dlc].hex()}; DLC: {dlc}; '
          f'Flags: {flags}; Handle: {handle}')

# Open a connection
with analib.channel.Channel() as ch:
    # Activate the callback function
    ch.setCallback(analib.wrapper.dll.CBFUNC(cbFunc))
    while True:
        # Do some more work here
        pass

Note that the arguments of the callback function are passed as Python build-in types except for the data bytes which come as a c_char POINTER() and needs to be converted to a bytes object first using the string_at() function. It is not possible to define c_char_p as argument type instead because it behaves differently and interprets bytes containing zero as terminating the byte sequence.