# Connect Python scripts to Ignition OPC server **URL:** \ **Category:** Ignition\ **Created:** [June 2, 2024, 6:22am UTC](https://forum.inductiveautomation.com/t/connect-python-scripts-to-ignition-opc-server/91250 "2024-06-02T06:22:08Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![R\_S](https://avatars.discourse-cdn.com/v4/letter/r/a88e57/32.png) [@R\_S](https://forum.inductiveautomation.com/u/R_S)\ **Post date:** [June 2, 2024, 6:22am UTC](https://forum.inductiveautomation.com/t/connect-python-scripts-to-ignition-opc-server/91250/1 "2024-06-02T06:22:08Z")
Continuing the discussion from [reading/Writing OPC tags from a python script outside Ignition](https://forum.inductiveautomation.com/t/reading-writing-opc-tags-from-a-python-script-outside-ignition/38665): Hey everyone, I found this old thread about connecting to Ignition's OPC sever and reading/writing tags with external Python scripts. After a bit of testing I thought I'd share my solution here in case it can save anyone some time. One of the reasons why you would use an external script is some Python libraries require C to work (looking at you SFTP), so this is a very basic example below that would allow you to read and write some types of OPC memory tags externally. Issues: - I do not know how to read/write datetime tags. They seem to read the value back as None. A workarounds for this that I've used is to read/write to a string tag and then convert with an expression tag within Ignition. - Same as above for datasets. Workaround is creating individual data point tags. Before you run your script, ,make sure you: 1. Install the OPC-UA Python library (pip install opcua) first 2. Expose the Ignition OPC-UA server to external connections ([Ignition's OPC UA Server | Ignition User Manual](https://www.docs.inductiveautomation.com/docs/8.1/ignition-modules/opc-ua/ignitions-opc-ua-server)): quickest way is set bind address to 0.0.0.0 and set expose tag providers to true. 3. Create new credentials to connect to the OPC-UA server with. Then you can use the below functions in an external script: ```python from opcua import Client def read_opc_val(server_url,tag_path): client = Client(server_url) result = {} try: client.connect() tag = client.get_node(f"ns=2;s={tag_path}").get_data_value() result["quality"] = tag.StatusCode result["value"] = tag.Value.Value result["variant"] = tag.Value.VariantType result["dimensions"] = tag.Value.Dimensions result["timestamp"] = tag.SourceTimestamp finally: client.disconnect() return result def write_opc_val(server_url,tag_path,write_val): client = Client(server_url) try: client.connect() client.get_node(f"ns=2;s={tag_path}").set_value(write_val) finally: client.disconnect() def write_opc_vals(server_url,tag_path_list,write_val_list): client = Client(server_url) try: client.connect() for i, tag_path in enumerate(tag_path_list): client.get_node(f"ns=2;s={tag_path}").set_value(write_val_list[i]) finally: client.disconnect() ##### opc_username = "your username here" opc_password = "your password here" server_ip = "ignition server ip here" opc_port = "your opc port here" # default = 62541 server_url = f"opc.tcp://{opc_username}:{opc_password}@{server_ip}:{opc_port}/discovery" # read tag_path = "[default]folder/tag_name" # copy tag path here example_value = read_opc_val(server_url,tag_path) # write tag_path = "[default]folder/tag_name" # copy tag path here write_val = "your new value" write_opc_val(server_url,tag_path,write_val) # write multiple at once tag_path_list = [ "[default]folder/tag_name1", # copy tag path here "[default]folder/tag_name2" # copy tag path here ] write_val_list = [ "value 1", "value 2" ] write_opc_vals(server_url,tag_path_list,write_val_list) ``` If you've read this far, perhaps you can help me with reading/writing to datetime and dataset tags? ---
**Author:** ![Rick\_de\_Man](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/rick_de_man/32/75670_2.png) [@Rick\_de\_Man](https://forum.inductiveautomation.com/u/Rick_de_Man)\ **Post date:** [June 2, 2024, 7:17am UTC](https://forum.inductiveautomation.com/t/connect-python-scripts-to-ignition-opc-server/91250/2 "2024-06-02T07:17:38Z")
I think the timestamps value in a Tag/OPC do not have the same source and work different? You can however write tags (value, timestamp, Quality etc..) directly using the WebDev module, maybe this is an option? ---
**Author:** ![jc-9](https://avatars.discourse-cdn.com/v4/letter/j/8e7dd6/32.png) [@jc-9](https://forum.inductiveautomation.com/u/jc-9)\ **Post date:** [July 29, 2024, 11:11pm UTC](https://forum.inductiveautomation.com/t/connect-python-scripts-to-ignition-opc-server/91250/3 "2024-07-29T23:11:23Z")
This is great! But Im having trouble making a connection with the OPC-UA server (getting timeout errors). Could you share some more detail on your Ignition settings? - Security - Are you using a security policy (i.e Basic256Sha256)? If so, how are you passing this certificate to Ignition though python? - Endpoint Address - opc.tcp://localhost:62541/discovery, is it OK if the port number is the same as other devices connecting to the server? In other words, can multiple devices connect to the OPCUA sever though the same port? ---
**Author:** ![blackriver](https://avatars.discourse-cdn.com/v4/letter/b/e47c2d/32.png) [@blackriver](https://forum.inductiveautomation.com/u/blackriver)\ **Post date:** [June 16, 2025, 7:17pm UTC](https://forum.inductiveautomation.com/t/connect-python-scripts-to-ignition-opc-server/91250/4 "2025-06-16T19:17:04Z")
FYI This was creating some hardship for me and I've created a set of scripts to traverse an OPCUA tag tree that should be helpful for others. > **[GitHub - palisadoes/opcua-ignition: Sample Python 3 Scripts for Interacting with...](https://github.com/palisadoes/opcua-ignition)** > > Sample Python 3 Scripts for Interacting with Inductive Automation's Ignition OPCUA API Server