fix-modbus-offset.py

#!/usr/bin/env python3

import sys
import json
import argparse
import os.path

DEFAULT_CONFIG_NEW = "/var/www/revpi/pictory/projects/_config.rsc"
DEFAULT_CONFIG_OLD = "/var/www/pictory/projects/_config.rsc"


def current_offset(io):
    return int(io[3])


def next_offset(io):
    current_offset = int(io[3])
    length = int(io[2]) / 8

    return int(current_offset + length)


def fix_memory(io, delta):
    io[3] = str(int(io[3]) - delta)

    return io


def write_configuration(config, filename):
    print(f"Writing changes to configuration file '{filename}'...")

    with open(filename, "w") as f:
        json.dump(config, f)


parser = argparse.ArgumentParser(
    description='Fix wrong offset of ModbusRTUMaster in Pictory config file')
parser.add_argument('-m', '--modify', action='store_true', dest='modify_config',
                    default=False, help='modify configuration file', required=False)
parser.add_argument('-f', '--filename', metavar='PICTORY_CONFIGURATION_FILE',
                    help='path to pictory configuration file', required=False, default=None)

args = parser.parse_args()

# try default configuration files
if args.filename is None:
    # new path since Buster
    if os.path.isfile(DEFAULT_CONFIG_NEW):
        args.filename = DEFAULT_CONFIG_NEW
    # old path Stretch and older
    elif os.path.isfile(DEFAULT_CONFIG_OLD):
        args.filename = DEFAULT_CONFIG_OLD
    else:
        print("Could not automatically detect the default pictory configuration file. Please specify a file with the argument '-f'")
        sys.exit(1)

    print(f"No configuration file specified. Using '{args.filename}' as default")


if not os.path.isfile(args.filename):
    print(f"configuration file '{args.filename}' does not exist")
    sys.exit(2)

with open(args.filename, 'r') as f:
    data = json.load(f)

num_changes = 0
for device in data.get("Devices", []):
    # only check for ModbusRTUMaster
    if device['productType'] != "24580" or not device['id'].startswith('device_ModbusRTUMaster_20180122_1_1_'):
        continue

    print(f"Checking device '{device['id']}' ...")

    # get last offset + length of last output
    last_output = device['out'][max(device['out'].keys())]

    offset_first_mem = next_offset(last_output)

    offset_calculated = offset_first_mem
    for idx_m, memory in device['mem'].items():
        offset = current_offset(memory)

        if offset > offset_calculated:
            delta = offset - offset_calculated

            print(f"  found offset in memory configuration '{memory[0]}': {delta} bytes")

            memory = fix_memory(memory, delta)
            num_changes += 1

        offset_calculated = next_offset(memory)

    if not num_changes:
        print("  no changes necessary")


if num_changes:
    print()

    if args.modify_config:
        try:
            write_configuration(data, args.filename)
        except IOError as e:
            print(f"ERROR: Could not write configuration file. Please make sure that you have write permissions to this file.")
            sys.exit(3)
    else:
        print(f"NOTE: The configuration file has not been modified. To apply {num_changes} modifications run again with argument '-m'")

1. Login on your RevPi via SSH
2. Download the script to your RevPi:

wget https://gist.github.com/nbuchwitz/7c7f335456db691c986fce70e657ce6b/raw/5d77381b9b4b09c328a818ba9bc62c76415de4d0/fix-modbus-offset.py -O /home/pi/fix-modbus-offset.py

3. Run the script without changing anything:

python3 /home/pi/fix-modbus-offset.py

4. Run the script as super user and write changes:

sudo python3 /home/pi/fix-modbus-offset.py --modify

The output should look similar to this one:

No configuration file specified. Using '/var/www/revpi/pictory/projects/_config.rsc' as default
Checking device 'device_ModbusRTUMaster_20180122_1_1_001' ...
  found offset in memory configuration 'baud_rate': 2 bytes
  found offset in memory configuration 'parity': 2 bytes
  found offset in memory configuration 'data_bits': 2 bytes
  found offset in memory configuration 'stop_bits': 2 bytes
Checking device 'device_ModbusRTUMaster_20180122_1_1_002' ...
  found offset in memory configuration 'baud_rate_i04': 2 bytes
  found offset in memory configuration 'parity_i04': 2 bytes
  found offset in memory configuration 'data_bits_i04': 2 bytes
  found offset in memory configuration 'stop_bits_i04': 2 bytes
Checking device 'device_ModbusRTUMaster_20180122_1_1_003' ...
  found offset in memory configuration 'baud_rate_i05': 2 bytes
  found offset in memory configuration 'parity_i05': 2 bytes
  found offset in memory configuration 'data_bits_i05': 2 bytes
  found offset in memory configuration 'stop_bits_i05': 2 bytes

Writing changes to configuration file '/var/www/revpi/pictory/projects/_config.rsc'...