Unable to gRPC remotely with Python

RXQ · September 2023

I have configured my controller AXCF 3152 (2022.6) for remote gRPC and confirmed this works via Output.log and grpcurl.

With Python I get errors. I am unable to figure out why this is.

Any pointers?

warnings.warn(

Traceback (most recent call last):

File ".\plcnext.py", line 41, in <module>

stub.ReadSingle(request)

File "D:\...\grpc\PLCnext\python\.venv\lib\site-packages\grpc\_channel.py", line 1161, in __call__

return _end_unary_response_blocking(state, call, False, None)

File "D:\...\grpc\PLCnext\python\.venv\lib\site-packages\grpc\_channel.py", line 1004, in _end_unary_response_blocking

raise _InactiveRpcError(state) # pytype: disable=not-instantiable

grpc._channel._InactiveRpcError: <_InactiveRpcError of RPC that terminated with:

status = StatusCode.UNAVAILABLE

details = "failed to connect to all addresses; last error: UNAVAILABLE: ipv4:192.168.2.2:50051: End of TCP stream"

debug_error_string = "UNKNOWN:failed to connect to all addresses; last error: UNAVAILABLE: ipv4:192.168.2.2:50051: End of TCP stream {grpc_status:14, created_time:"2023-09-25T10:07:25.1373492+00:00"}"

Pipenv:

[[source]]

url = "https://pypi.org/simple"

verify_ssl = true

name = "pypi"

[packages]

grpcio = "*"

grpcio-tools = "*"

requests = "*"

[dev-packages]

[requires]

python_version = "3.8"

Imports in .py:

import requests

import grpc

# Import the PLCnext gRPC service's protocol definition file.

import Plc.Gds.ISubscriptionService_pb2_grpc as SubStub

import Plc.Gds.ISubscriptionService_pb2 as Sub

import Plc.Gds.SubscriptionKind_pb2 as SubKind

import Plc.Gds.IDataAccessService_pb2_grpc as DAStub

import Plc.Gds.IDataAccessService_pb2 as DA

Actual code:

channel = grpc.insecure_channel('192.168.2.2:50051')

stub = DAStub.IDataAccessServiceStub(channel)

request = DA.IDataAccessServiceReadSingleRequest()

request.portName = 'Arp.Plc.Eclr/MainInstance.MY_INT'

stub.ReadSingle(request)

print(response)

channel.close()

RXQ · September 2023

Thanks, it was resolved with a little help from Phoenix Contact.

The insecure_channel was not enough to establish a connection with the server. I needed a secure_channel with a self-signed certificate.

with open("server.crt", "rb") as f:

ca_cert = f.read()

channel = grpc.secure_channel('10.0.21.111:50051', grpc.ssl_channel_credentials(ca_cert))

To acquire a certificate, the steps are described here:

https://www.plcnext-community.net/makersblog/secure-remote-grpc-using-grpcurl/

Unable to gRPC remotely with Python

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