Multiple node read in single request from client in open62541

Question

Can anyone tell me the syntax for multiple node read in single request to server in open62541.

i have been doing a single read request by UA_Client_readValueAttribute(client, UA_NODEID_STRING(1, "variable"), &value) from the open62541 client to server.

Answer 1

You can use the standard read service:

UA_Client_Service_read(UA_Client *client, const UA_ReadRequest request)

See: https://github.com/open62541/open62541/blob/6c82b082c8a6c3b1faebc43387a1b0cb3eced051/include/ua_client.h#L203

E.g.:

UA_ReadRequest request;
UA_ReadRequest_init(&request);
UA_ReadValueId ids[2];
UA_ReadValueId_init(&ids[0]);
ids[0].attributeId = UA_ATTRIBUTEID_VALUE;
ids[0].nodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_SERVER_NAMESPACEARRAY);

UA_ReadValueId_init(&ids[1]);
ids[1].attributeId = UA_ATTRIBUTEID_VALUE;
ids[1].nodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_SERVER_STATUS);

// set here the nodes you want to read
request.nodesToRead = ids;
request.nodesToReadSize = 2;

UA_ReadResponse response = UA_Client_Service_read(client, request);

// do something with the response

---

Crosspost: https://github.com/open62541/open62541/issues/1426