Standard-Defined Constants

This section contains numerical and string constants that are defined in the OPC UA standard.

Attribute Id

Every node in an OPC UA information model contains attributes depending on the node type. Possible attributes are as follows:

typedef enum {
    UA_ATTRIBUTEID_NODEID                  = 1,
    UA_ATTRIBUTEID_NODECLASS               = 2,
    UA_ATTRIBUTEID_BROWSENAME              = 3,
    UA_ATTRIBUTEID_DISPLAYNAME             = 4,
    UA_ATTRIBUTEID_DESCRIPTION             = 5,
    UA_ATTRIBUTEID_WRITEMASK               = 6,
    UA_ATTRIBUTEID_USERWRITEMASK           = 7,
    UA_ATTRIBUTEID_ISABSTRACT              = 8,
    UA_ATTRIBUTEID_SYMMETRIC               = 9,
    UA_ATTRIBUTEID_INVERSENAME             = 10,
    UA_ATTRIBUTEID_CONTAINSNOLOOPS         = 11,
    UA_ATTRIBUTEID_EVENTNOTIFIER           = 12,
    UA_ATTRIBUTEID_VALUE                   = 13,
    UA_ATTRIBUTEID_DATATYPE                = 14,
    UA_ATTRIBUTEID_VALUERANK               = 15,
    UA_ATTRIBUTEID_ARRAYDIMENSIONS         = 16,
    UA_ATTRIBUTEID_ACCESSLEVEL             = 17,
    UA_ATTRIBUTEID_USERACCESSLEVEL         = 18,
    UA_ATTRIBUTEID_MINIMUMSAMPLINGINTERVAL = 19,
    UA_ATTRIBUTEID_HISTORIZING             = 20,
    UA_ATTRIBUTEID_EXECUTABLE              = 21,
    UA_ATTRIBUTEID_USEREXECUTABLE          = 22,
    UA_ATTRIBUTEID_DATATYPEDEFINITION      = 23
} UA_AttributeId;

Access Level Masks

The access level to a node is given by the following constants that are ANDed with the overall access level.

#define UA_ACCESSLEVELMASK_READ           (0x01u << 0u)
#define UA_ACCESSLEVELMASK_WRITE          (0x01u << 1u)
#define UA_ACCESSLEVELMASK_HISTORYREAD    (0x01u << 2u)
#define UA_ACCESSLEVELMASK_HISTORYWRITE   (0x01u << 3u)
#define UA_ACCESSLEVELMASK_SEMANTICCHANGE (0x01u << 4u)
#define UA_ACCESSLEVELMASK_STATUSWRITE    (0x01u << 5u)
#define UA_ACCESSLEVELMASK_TIMESTAMPWRITE (0x01u << 6u)

Write Masks

The write mask and user write mask is given by the following constants that are ANDed for the overall write mask. Part 3: 5.2.7 Table 2

#define UA_WRITEMASK_ACCESSLEVEL             (0x01u << 0u)
#define UA_WRITEMASK_ARRRAYDIMENSIONS        (0x01u << 1u)
#define UA_WRITEMASK_BROWSENAME              (0x01u << 2u)
#define UA_WRITEMASK_CONTAINSNOLOOPS         (0x01u << 3u)
#define UA_WRITEMASK_DATATYPE                (0x01u << 4u)
#define UA_WRITEMASK_DESCRIPTION             (0x01u << 5u)
#define UA_WRITEMASK_DISPLAYNAME             (0x01u << 6u)
#define UA_WRITEMASK_EVENTNOTIFIER           (0x01u << 7u)
#define UA_WRITEMASK_EXECUTABLE              (0x01u << 8u)
#define UA_WRITEMASK_HISTORIZING             (0x01u << 9u)
#define UA_WRITEMASK_INVERSENAME             (0x01u << 10u)
#define UA_WRITEMASK_ISABSTRACT              (0x01u << 11u)
#define UA_WRITEMASK_MINIMUMSAMPLINGINTERVAL (0x01u << 12u)
#define UA_WRITEMASK_NODECLASS               (0x01u << 13u)
#define UA_WRITEMASK_NODEID                  (0x01u << 14u)
#define UA_WRITEMASK_SYMMETRIC               (0x01u << 15u)
#define UA_WRITEMASK_USERACCESSLEVEL         (0x01u << 16u)
#define UA_WRITEMASK_USEREXECUTABLE          (0x01u << 17u)
#define UA_WRITEMASK_USERWRITEMASK           (0x01u << 18u)
#define UA_WRITEMASK_VALUERANK               (0x01u << 19u)
#define UA_WRITEMASK_WRITEMASK               (0x01u << 20u)
#define UA_WRITEMASK_VALUEFORVARIABLETYPE    (0x01u << 21u)

ValueRanks

The following are the most common ValueRanks used for Variables, VariableTypes and method arguments. ValueRanks higher than 3 are valid as well (but less common).

#define UA_VALUERANK_SCALAR_OR_ONE_DIMENSION  -3
#define UA_VALUERANK_ANY                      -2
#define UA_VALUERANK_SCALAR                   -1
#define UA_VALUERANK_ONE_OR_MORE_DIMENSIONS    0
#define UA_VALUERANK_ONE_DIMENSION             1
#define UA_VALUERANK_TWO_DIMENSIONS            2
#define UA_VALUERANK_THREE_DIMENSIONS          3

Internal Definitions

Rule Handling

The RuleHanding settings define how error cases that result from rules in the OPC UA specification shall be handled. The rule handling can be softened, e.g. to workaround misbehaving implementations or to mitigate the impact of additional rules that are introduced in later versions of the OPC UA specification.

typedef enum {
    UA_RULEHANDLING_DEFAULT = 0,
    UA_RULEHANDLING_ABORT,  /* Abort the operation and return an error code */
    UA_RULEHANDLING_WARN,   /* Print a message in the logs and continue */
    UA_RULEHANDLING_ACCEPT, /* Continue and disregard the broken rule */
} UA_RuleHandling;

Order

The Order enum is used to establish an absolute ordering between elements.

typedef enum {
    UA_ORDER_LESS = -1,
    UA_ORDER_EQ = 0,
    UA_ORDER_MORE = 1
} UA_Order;

Statistic counters

The stack manage statistic counter for the following layers: - Network - Secure channel - Session

The session layer counters are matching the counters of the ServerDiagnosticsSummaryDataType that are defined in the OPC UA Part 5 specification. Counter of the other layers are not specified by OPC UA but are harmonized with the session layer counters if possible.

typedef struct {
    size_t currentConnectionCount;
    size_t cumulatedConnectionCount;
    size_t rejectedConnectionCount;
    size_t connectionTimeoutCount;
    size_t connectionAbortCount;
} UA_NetworkStatistics;

typedef struct {
    size_t currentChannelCount;
    size_t cumulatedChannelCount;
    size_t rejectedChannelCount;
    size_t channelTimeoutCount; /* only used by servers */
    size_t channelAbortCount;
    size_t channelPurgeCount;   /* only used by servers */
} UA_SecureChannelStatistics;

typedef struct {
    size_t currentSessionCount;
    size_t cumulatedSessionCount;
    size_t securityRejectedSessionCount; /* only used by servers */
    size_t rejectedSessionCount;
    size_t sessionTimeoutCount;          /* only used by servers */
    size_t sessionAbortCount;            /* only used by servers */
} UA_SessionStatistics;