The method being called is a direct child object yes. In practice I’m saving the node id of the object into a temporary variable and then retrieving the methods with the GetMethods() method. While I am using the DI-companion specification I’ve opted against a MethodSet for these specific objects. What makes things more confusing is that the method can be invoked just fine with the Browser which narrows the issue down to my implementation of the client.

I don’t know if this will help but here is the relevant section for browsing the address space (barring sections commented out during testing and variable declarations):

//Connect to the chosen server
connect(tmpClient);
tmpClient.getAddressSpace().setMaxReferencesPerNode(1000);
tmpClient.getAddressSpace().setReferenceTypeId(Identifiers.HierarchicalReferences);

//Browse the address space to get the namespace table and device skills
tmpSpace = tmpClient.getAddressSpace();
refDescs = tmpSpace.browse(Identifiers.ObjectsFolder);
tmpTable = tmpSpace.getNamespaceTable();

//Iterate to find the device Set
for(ReferenceDescription tempRef : refDescs) {
if(tempRef.getDisplayName().getText().equals(“DeviceSet”)) {
tmpId = tmpTable.toNodeId(tempRef.getNodeId());
}
}

//Iterate again to find Device Skills
refDescs = tmpSpace.browse(tmpId);
for(ReferenceDescription tempRef : refDescs) {
if(tempRef.getDisplayName().getText().contains(“DeviceSkills”)) {
tmpId = tmpTable.toNodeId(tempRef.getNodeId());
}
}

//Get refs from DeviceSkills to build list of skills
skillRefs = new ArrayList();
refDescs = tmpSpace.browse(tmpId);
for(ReferenceDescription tempRef : refDescs) {
if(tempRef.getNodeClass().toString().equals(“Object”)) {
skillRefs.add(tempRef);
}
}

//Browse the methods
for (ReferenceDescription tempRef : skillRefs) {
if (tempRef.getDisplayName().getText().contains(skillName)) {
skillId = tmpTable.toNodeId(tempRef.getNodeId());
skillMethods = tmpSpace.getMethods(skillId);
}
}

//Get method id
for(UaMethod tempSkill : skillMethods) {
if (tempSkill.getDisplayName().getText().contains(action)) {
testId = tempSkill.getNodeId();
}
}

//Call selected method
Variant[] outputs = tmpClient.call(skillId,testId);
System.out.println(“Method output: ” + outputs);

I must apologize for the long-windedness however at the time I could not think of a more elegant method of retrieving the selected object and method except for browsing the address space a layer at a time. SkillName and action are strings which are previously selected names of objects in the hierarchy. I would also like to apologize for the formatting as the forums are eating my indentation for some unknown reason.

It would appear that a part of my initial diagnosis of the issue was wrong. I made minor modifications so that instead of calling the method with the saved NodeIds as input paramters I instead re-retrieved the nodes from the address space before getting their NodeId:s. I am still getting the same Bad_MethodInvalid call status exceptions however quite confusingly the server method handler is still executing the method that was called.

I will continue tweaking the code to see if I can find a solution. Thank you for taking the time to help with troubleshooting.

EDIT: I have found the cause. It was actually nothing to do with the method call itself. The device server method handler was set to return a failed result in case it was unable to contact the PLC corresponding to the server. For some reason the client interpreted this instead as a MethodInvalid error. This issue is resolved and was entirely due to a mistake (maybe?) I made in an entirely different part of the code.