# OPC UA Method call hangs **URL:** \ **Category:** Ignition\ **Tags:** ignition81\ **Created:** [March 30, 2023, 2:52pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836 "2023-03-30T14:52:41Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 2:52pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/1 "2023-03-30T14:52:42Z")
Hi all, I'm trying to call an OPC Method with the `system.opcua.callMethod`. My network configuration is as follows: - PC1 with Ignition Designer and OPC UA Expert Client - PC2 with Ignition Gateway - PC3 with the OPC UA Server I can call the OPC UA Method on PC3 from _OPC UA Expert Client_ on PC1, whereas the Ignition Python function where I've programmed the `callMethod` cannot. The Python function is called by a `ValueChanged` event on an Ignition Gateway Tag, so that `callMethod` runs on the Gateway as required by the function scope spec: ```auto def getZ020WS(jsonInput): logger.info('>>>>>>> %s' % jsonInput) res=system.opcua.callMethod( connectionName="OpcRouter" ,objectId= "ns=2;s=MyResources" ,methodId= "ns=2;s=MyResources.getZ020WS" ,inputs=[jsonInput]) logger.info('>>>>>>> CALL END %s' % res) ``` Reading through the wrapper.log I don't find any exception logged. Moreover the first log entry before the `callMethod` is there, whereas the second one where I try to log the `callMethod` result is not. If I run the same function on a PC which is running all the system components (Ignition, OPC Server, Desginer, OPC UA Client), it works perfectly. Any suggestion? I don't think it's a matter of firewalls, becuase _OPC UA Expert Client_ manages to do the call. Thanks in davance, regards Ignition version: 8.1.25 (b2023021409) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 2:56pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/2 "2023-03-30T14:56:14Z")
How long does it hang? Can you get a thread dump while it's hung? Can you get a Wireshark capture, made on either PC2 or PC3, with security for the connection turned off? ---
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 3:26pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/3 "2023-03-30T15:26:08Z")
> [@Kevin.Herron](#): > > How long does it hang? Hi Kevin, thanks for your reply. It hangs indefinitely, i.e. I never see the `>>>>>> CALL END` log entry. One more note: If I try to write a value from the tag browser directly into a tag in the OPC UA Address space, that's no problem: the tag new value is written correctly and I see the new value in the _OPC UA Expert Client_. I've given a try also to next code, which I took from Ignition help: ```auto result = system.opcua.callMethod( "Ignition OPC UA Server", "ns=0;i=2253", "ns=0;i=11492", [1] ) ``` but behavior is just the same: the code never arrives at the `>>>>> CALL END` log entry. I'm sure I'm doing something wrong, but I don't know where. I will speak with the customer to see if I may capture Ethernet traffic with Wireshark and I will be back to you. Thanks, regards ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 3:29pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/4 "2023-03-30T15:29:09Z")
`callMethod` will throw an Exception if the call times out (or in some other error scenarios), which it should after ~60sec or whatever the request timeout on the connection is configured for. You won't see your final logging statement when this happens. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 3:30pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/5 "2023-03-30T15:30:36Z")
You might also get a little more info in the logs by setting the logger `opcua.gateway.scripting.CallMethod` to DEBUG level. ---
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 4:29pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/6 "2023-03-30T16:29:10Z")
I @Kevin.Herron , just set the logger to `DEBUG` but got no further information. I've installed _MS Network Monitor_ and saw that when _OPC UA Expert_ calls the method, the monitor shows meaningful records (attached) [OPCUaExpertTraffic.cap](https://forum.inductiveautomation.com/uploads/short-url/qt387vnPGL0IRQrcCuEWka4zHQT.cap) (7.1 KB) Whereas nothing interesting appears when the call should come from Ignition, as if the call does not get out of Ignition. Maybe I'm wrong in the _OPC UA Server_ connection configuration - e.g. I had to uncheck the _Certificate Validation Enabled_ property to get the connection UP and running. If you have further ideas, I thank you. Regards ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 4:31pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/7 "2023-03-30T16:31:07Z")
Are you sure you've got the correct connection name? Is the status of that connection good/connected? ---
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 4:36pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/8 "2023-03-30T16:36:09Z")
> [@Kevin.Herron](#): > > correct connection name? I think so: ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/3/d/3ddb2e7bf6105875da30c9f5c5a011f0444af113.png) On the left you see the name of the _OPC Connection_ as shown in the gateweay configuration and on the right my function call. The OPC Connection shows up as _Connected_, provided that I uncheck the _Certificate Validation_ option. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 4:37pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/9 "2023-03-30T16:37:16Z")
I don't know, there's something suspect going on if you can't even get any log entries from that logger. ---
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 4:39pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/10 "2023-03-30T16:39:27Z")
You are right, but why this piece of code does nothing either: ```auto result = system.opcua.callMethod( "Ignition OPC UA Server", "ns=0;i=2253", "ns=0;i=11492", [1] ) ``` Not sure, but I think it should work as is, with no further configuration, shouldn't it? ---
**Author:** ![avaughn](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/avaughn/32/38972_2.png) [@avaughn](https://forum.inductiveautomation.com/u/avaughn)\ **Post date:** [March 30, 2023, 4:41pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/11 "2023-03-30T16:41:37Z")
Do you have a logger object created with `system.util.getLogger()` before you try to use `logger.info()` on line 7? ---
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 4:42pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/12 "2023-03-30T16:42:25Z")
> [@avaughn](#): > > Do you have a logger object Yes of course, and I see it works in the wrapper.log ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 4:42pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/13 "2023-03-30T16:42:47Z")
I put this into a tag event script: ```auto print "calling method..." result = system.opcua.callMethod( "Ignition OPC UA Server", "ns=0;i=2253", "ns=0;i=11492", [1] ) print result ``` and in my (wrapper) logs I get: ```auto calling method... ((2150105088L, u'Bad_SubscriptionIdInvalid', u'The subscription id is not valid.'), [], []) ``` ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 4:43pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/14 "2023-03-30T16:43:55Z")
You seem to be writing code in a project script module - is that project set as the Gateway Scripting Project? ---
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 4:46pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/15 "2023-03-30T16:46:22Z")
... just what I'd like to see. As I told you, I put a test PC together, where Ignition and the OPC UA Server were on the same PC: my code worked like a charm and I got the answer you pointed to and the answer from my `getZ020WS` OPC UA Method too. On the contrary the customer's distributed configuration does not work ---
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 4:47pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/16 "2023-03-30T16:47:29Z")
> [@Kevin.Herron](#): > > is that project set as the Gateway Scripting Project Yes, other wise I would get no log at all, neither the very first entry `>>>>>>> ....` ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 4:49pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/17 "2023-03-30T16:49:11Z")
Try wrapping the whole thing in [try/catch](https://forum.inductiveautomation.com/t/catch-ioexception/18612/3) and logging any exceptions that get caught. Also get a thread dump from the gateway after you've made the call, we'll be able to see if it's actually hanging or not. ---
**Author:** ![pgmo](https://avatars.discourse-cdn.com/v4/letter/p/d07c76/32.png) [@pgmo](https://forum.inductiveautomation.com/u/pgmo)\ **Post date:** [March 30, 2023, 4:52pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/18 "2023-03-30T16:52:47Z")
> [@Kevin.Herron](#): > > Try wrapping the whole thing in [try/catch](https://forum.inductiveautomation.com/t/catch-ioexception/18612/3) Tried already: the `catch` branch with a `print e.getCause()` doesn't seem to be executed at all. > Also get a thread dump from the gateway Could you guide me to get the thread dump? Thanks ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 4:55pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/19 "2023-03-30T16:55:17Z")
They can be downloaded from the threads diagnostics page in the gateway. [https://docs.inductiveautomation.com/display/DOC81/Diagnostics+-+Threads#DiagnosticsThreads-IndividualThreads](https://docs.inductiveautomation.com/display/DOC81/Diagnostics+-+Threads#DiagnosticsThreads-IndividualThreads) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [March 30, 2023, 5:01pm UTC](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836/20 "2023-03-30T17:01:15Z")
Oh, another thing I should have caught earlier... `callMethod` doesn't take keyword-args like you're trying to call it with. You should be seeing a big ol' error in the logs about this... [Next page](https://forum.inductiveautomation.com/t/opc-ua-method-call-hangs/71836.md?page=2)