tutorial_server_variable.c 4.5 KB

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  1. /* This work is licensed under a Creative Commons CCZero 1.0 Universal License.
  2. * See http://creativecommons.org/publicdomain/zero/1.0/ for more information. */
  3. /**
  4. * Adding Variables to a Server
  5. * ----------------------------
  6. *
  7. * This tutorial shows how to work with data types and how to add variable nodes
  8. * to a server. First, we add a new variable to the server. Take a look at the
  9. * definition of the ``UA_VariableAttributes`` structure to see the list of all
  10. * attributes defined for VariableNodes.
  11. *
  12. * Note that the default settings have the AccessLevel of the variable value as
  13. * read only. See below for making the variable writable.
  14. */
  15. #include <open62541/plugin/log_stdout.h>
  16. #include <open62541/server.h>
  17. #include <open62541/server_config_default.h>
  18. #include <signal.h>
  19. #include <stdlib.h>
  20. static void
  21. addVariable(UA_Server *server) {
  22. /* Define the attribute of the myInteger variable node */
  23. UA_VariableAttributes attr = UA_VariableAttributes_default;
  24. UA_Int32 myInteger = 42;
  25. UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
  26. attr.description = UA_LOCALIZEDTEXT("en-US","the answer");
  27. attr.displayName = UA_LOCALIZEDTEXT("en-US","the answer");
  28. attr.dataType = UA_TYPES[UA_TYPES_INT32].typeId;
  29. attr.accessLevel = UA_ACCESSLEVELMASK_READ | UA_ACCESSLEVELMASK_WRITE;
  30. /* Add the variable node to the information model */
  31. UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
  32. UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(1, "the answer");
  33. UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);
  34. UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES);
  35. UA_Server_addVariableNode(server, myIntegerNodeId, parentNodeId,
  36. parentReferenceNodeId, myIntegerName,
  37. UA_NODEID_NUMERIC(0, UA_NS0ID_BASEDATAVARIABLETYPE), attr, NULL, NULL);
  38. }
  39. /**
  40. * Now we change the value with the write service. This uses the same service
  41. * implementation that can also be reached over the network by an OPC UA client.
  42. */
  43. static void
  44. writeVariable(UA_Server *server) {
  45. UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
  46. /* Write a different integer value */
  47. UA_Int32 myInteger = 43;
  48. UA_Variant myVar;
  49. UA_Variant_init(&myVar);
  50. UA_Variant_setScalar(&myVar, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
  51. UA_Server_writeValue(server, myIntegerNodeId, myVar);
  52. /* Set the status code of the value to an error code. The function
  53. * UA_Server_write provides access to the raw service. The above
  54. * UA_Server_writeValue is syntactic sugar for writing a specific node
  55. * attribute with the write service. */
  56. UA_WriteValue wv;
  57. UA_WriteValue_init(&wv);
  58. wv.nodeId = myIntegerNodeId;
  59. wv.attributeId = UA_ATTRIBUTEID_VALUE;
  60. wv.value.status = UA_STATUSCODE_BADNOTCONNECTED;
  61. wv.value.hasStatus = true;
  62. UA_Server_write(server, &wv);
  63. /* Reset the variable to a good statuscode with a value */
  64. wv.value.hasStatus = false;
  65. wv.value.value = myVar;
  66. wv.value.hasValue = true;
  67. UA_Server_write(server, &wv);
  68. }
  69. /**
  70. * Note how we initially set the DataType attribute of the variable node to the
  71. * NodeId of the Int32 data type. This forbids writing values that are not an
  72. * Int32. The following code shows how this consistency check is performed for
  73. * every write.
  74. */
  75. static void
  76. writeWrongVariable(UA_Server *server) {
  77. UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
  78. /* Write a string */
  79. UA_String myString = UA_STRING("test");
  80. UA_Variant myVar;
  81. UA_Variant_init(&myVar);
  82. UA_Variant_setScalar(&myVar, &myString, &UA_TYPES[UA_TYPES_STRING]);
  83. UA_StatusCode retval = UA_Server_writeValue(server, myIntegerNodeId, myVar);
  84. printf("Writing a string returned statuscode %s\n", UA_StatusCode_name(retval));
  85. }
  86. /** It follows the main server code, making use of the above definitions. */
  87. UA_Boolean running = true;
  88. static void stopHandler(int sign) {
  89. UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");
  90. running = false;
  91. }
  92. int main(void) {
  93. signal(SIGINT, stopHandler);
  94. signal(SIGTERM, stopHandler);
  95. UA_ServerConfig *config = UA_ServerConfig_new_default();
  96. UA_Server *server = UA_Server_new(config);
  97. addVariable(server);
  98. writeVariable(server);
  99. writeWrongVariable(server);
  100. UA_StatusCode retval = UA_Server_run(server, &running);
  101. UA_Server_delete(server);
  102. UA_ServerConfig_delete(config);
  103. return retval == UA_STATUSCODE_GOOD ? EXIT_SUCCESS : EXIT_FAILURE;
  104. }