Same context for created object

[titov32]

It's probably a question rather than a problem. The same context is used when creating objects, specifically self.identity = ModbusDeviceIdentification(). How to correctly use pymodbus to have different contexts?

Versions

• Python: 3.11
• OS: Debain
• Pymodbus: 3.6.3
• Modbus Hardware (if used):

Pymodbus Specific

• Server: UDP - async
• Client: udp - sync

Description

I create different class modbus server, change self.identity.ProductCode and other parametrs, but when I run them all get one context. I expected different object classes, but get one class.

Code and Logs

from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock, ModbusSlaveContext, ModbusServerContext
from pymodbus.server import StartAsyncUdpServer
import asyncio
from logger import info_log
import pymodbus

pymodbus.pymodbus_apply_logging_config("DEBUG")

class MirageBase:
    def __init__(self):
        super().__init__()
        self.store: ModbusSequentialDataBlock = ModbusSequentialDataBlock(0, [0] * 129)
        self.slave_context = ModbusSlaveContext(hr=self.store)
        self.context = ModbusServerContext(slaves=self.slave_context, single=True)
        self.identity = ModbusDeviceIdentification()
        self.identity.VendorName = 'Tornado\x00'

    async def change_register(self, address, value):
        while True:
            self.store.setValues(address, value)
            await asyncio.sleep(1)

    def read_register(self, address):
        r = self.store.getValues(address)[0]
        return r.registers

    async def run(self):
        info_log.info(f'Start Emulator IOD on IP address {self.ip_address}, model: {self.identity.ProductCode}')
        await StartAsyncUdpServer(self.context, identity=self.identity, address=(self.ip_address, 502))
        info_log.info(f'Stop Emulator IOD on IP address {self.ip_address}, model: {self.identity.ProductCode}')

class MirageNai(MirageBase):
    def __init__(self, ip_address):
        super().__init__()
        self.store: ModbusSequentialDataBlock = ModbusSequentialDataBlock(0, [0] * 129)
        self.ip_address = ip_address
        self.slave_context = ModbusSlaveContext(hr=self.store)
        self.context = ModbusServerContext(slaves=self.slave_context, single=True)

        # ниже информация которое будет выдавать устройство Nai
        self.identity = ModbusDeviceIdentification()
        self.identity.VendorName = 'Tornado\x00'
        self.identity.ProductCode = 'NAI'

class MirageNDI(MirageBase):
    """
    Mirage NDI, registers for use: 17-28 and 1001-1024
    """

    def __init__(self, ip_address):
        super().__init__()
        self.store: ModbusSequentialDataBlock = ModbusSequentialDataBlock(0, [0] * 1128)
        self.ip_address = ip_address
        self.slave_context = ModbusSlaveContext(hr=self.store)
        self.context = ModbusServerContext(slaves=self.slave_context, single=True)
        self.identity = ModbusDeviceIdentification()
        self.identity.VendorName = 'Tornado\x00'
        self.identity.ProductCode = 'NDI'

def create_coroutines(device_type) -> list:
    coroutines = []
    info_log.info(rf'Device type for create coroutine: {device_type}')
    match device_type:
        case 'NAI':
            mirage = MirageNai('10.2.11.2')
        case 'NDI':
            mirage = MirageNDI('10.2.11.9')
        case _:
            raise ValueError('Wrong Type Mirage')
    coroutines.append(mirage.run())
    return coroutines

async def main():
    list_coroutines = []
    devices = ['NDI', 'NAI']
    for device in devices:
        list_coroutines.extend(create_coroutines(device))
    await asyncio.gather(*list_coroutines)

if __name__ == '__main__':
    asyncio.run(main())

# please use the following to format logs when posting them here
import pymodbus

pymodbus.pymodbus_apply_logging_config("DEBUG")

2024-01-16 14:45:59,730 : info:70 : INFO : Device type for create coroutine: NDI 2024-01-16 14:45:59,732 : info:70 : INFO : Device type for create coroutine: NAI 2024-01-16 14:45:59,735 : info:30 : INFO : Start Emulator IOD on IP address 10.2.11.9, model: NAI 2024-01-16 14:45:59,735 DEBUG logging:103 Awaiting connections server_listener 2024-01-16 14:45:59,736 : info:30 : INFO : Start Emulator IOD on IP address 10.2.11.2, model: NAI 2024-01-16 14:45:59,736 DEBUG logging:103 Awaiting connections server_listener 2024-01-16 14:45:59,736 DEBUG logging:103 Connected to server 2024-01-16 14:45:59,736 DEBUG logging:103 Connected to server 2024-01-16 14:45:59,736 INFO logging:97 Server listening. 2024-01-16 14:45:59,736 INFO logging:97 Server listening.

[janiversen]

The server can pr definition only have 1 context! This is logical since 1 server == 1 device.

[janiversen]

Of course having different server objects would be 1 object = 1 device.

Currently the modbusIdentification is a singleton in the code and thus identical across all server objects.

Pull requests are welcome.

[titov32]

To run on a single device and obtain different contexts, is it necessary to use different instances of the program (docker and others), or is it possible to handle everything within one program?

[janiversen]

You need to start multiple programs....A singleton, means there are only 1 object in one program space.

[titov32]

Can you point out the place in the code where the singleton implementation is?

[janiversen]

"git grep ModbusDeviceIdentification" is your friend.

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[github-actions[bot]]

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