tutorial_server_variable.c 4.4 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_VariableAttrbitues`` 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 <signal.h>
  16. #include <stdio.h>
  17. #include "open62541.h"
  18. static void
  19. addVariable(UA_Server *server) {
  20. /* Define the attribute of the myInteger variable node */
  21. UA_VariableAttributes attr = UA_VariableAttributes_default;
  22. UA_Int32 myInteger = 42;
  23. UA_Variant_setScalar(&attr.value, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
  24. attr.description = UA_LOCALIZEDTEXT("en-US","the answer");
  25. attr.displayName = UA_LOCALIZEDTEXT("en-US","the answer");
  26. attr.dataType = UA_TYPES[UA_TYPES_INT32].typeId;
  27. attr.accessLevel = UA_ACCESSLEVELMASK_READ | UA_ACCESSLEVELMASK_WRITE;
  28. /* Add the variable node to the information model */
  29. UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
  30. UA_QualifiedName myIntegerName = UA_QUALIFIEDNAME(1, "the answer");
  31. UA_NodeId parentNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_OBJECTSFOLDER);
  32. UA_NodeId parentReferenceNodeId = UA_NODEID_NUMERIC(0, UA_NS0ID_ORGANIZES);
  33. UA_Server_addVariableNode(server, myIntegerNodeId, parentNodeId,
  34. parentReferenceNodeId, myIntegerName,
  35. UA_NODEID_NUMERIC(0, UA_NS0ID_BASEDATAVARIABLETYPE), attr, NULL, NULL);
  36. }
  37. /**
  38. * Now we change the value with the write service. This uses the same service
  39. * implementation that can also be reached over the network by an OPC UA client.
  40. */
  41. static void
  42. writeVariable(UA_Server *server) {
  43. UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
  44. /* Write a different integer value */
  45. UA_Int32 myInteger = 43;
  46. UA_Variant myVar;
  47. UA_Variant_init(&myVar);
  48. UA_Variant_setScalar(&myVar, &myInteger, &UA_TYPES[UA_TYPES_INT32]);
  49. UA_Server_writeValue(server, myIntegerNodeId, myVar);
  50. /* Set the status code of the value to an error code. The function
  51. * UA_Server_write provides access to the raw service. The above
  52. * UA_Server_writeValue is syntactic sugar for writing a specific node
  53. * attribute with the write service. */
  54. UA_WriteValue wv;
  55. UA_WriteValue_init(&wv);
  56. wv.nodeId = myIntegerNodeId;
  57. wv.attributeId = UA_ATTRIBUTEID_VALUE;
  58. wv.value.status = UA_STATUSCODE_BADNOTCONNECTED;
  59. wv.value.hasStatus = true;
  60. UA_Server_write(server, &wv);
  61. /* Reset the variable to a good statuscode with a value */
  62. wv.value.hasStatus = false;
  63. wv.value.value = myVar;
  64. wv.value.hasValue = true;
  65. UA_Server_write(server, &wv);
  66. }
  67. /**
  68. * Note how we initially set the DataType attribute of the variable node to the
  69. * NodeId of the Int32 data type. This forbids writing values that are not an
  70. * Int32. The following code shows how this consistency check is performed for
  71. * every write.
  72. */
  73. static void
  74. writeWrongVariable(UA_Server *server) {
  75. UA_NodeId myIntegerNodeId = UA_NODEID_STRING(1, "the.answer");
  76. /* Write a string */
  77. UA_String myString = UA_STRING("test");
  78. UA_Variant myVar;
  79. UA_Variant_init(&myVar);
  80. UA_Variant_setScalar(&myVar, &myString, &UA_TYPES[UA_TYPES_STRING]);
  81. UA_StatusCode retval = UA_Server_writeValue(server, myIntegerNodeId, myVar);
  82. printf("Writing a string returned statuscode %s\n", UA_StatusCode_name(retval));
  83. }
  84. /** It follows the main server code, making use of the above definitions. */
  85. UA_Boolean running = true;
  86. static void stopHandler(int sign) {
  87. UA_LOG_INFO(UA_Log_Stdout, UA_LOGCATEGORY_SERVER, "received ctrl-c");
  88. running = false;
  89. }
  90. int main(void) {
  91. signal(SIGINT, stopHandler);
  92. signal(SIGTERM, stopHandler);
  93. UA_ServerConfig *config = UA_ServerConfig_new_default();
  94. UA_Server *server = UA_Server_new(config);
  95. addVariable(server);
  96. writeVariable(server);
  97. writeWrongVariable(server);
  98. UA_StatusCode retval = UA_Server_run(server, &running);
  99. UA_Server_delete(server);
  100. UA_ServerConfig_delete(config);
  101. return (int)retval;
  102. }