ncGetDriverAttr (Get Driver Attribute)
Purpose
Get the value of an attribute in the NI-DNET driver.
Format
LabVIEW
C
| NCTYPE_STATUS | ncGetDriverAttr (NCTYPE_OBJH ObjHandle,
NCTYPE_ATTRID AttrId,
NCTYPE_UINT32 SizeofAttr,
NCTYPE_ANY_P Attr) |
Input
| ObjHandle | Object handle of an open Explicit Messaging Object, I/O Object, or Interface Object |
| AttrId | Identifier of the attribute to get |
| SizeofAttr | Size of the Attr buffer in bytes (C only) |
Output
| Attr | Returned attribute value |
Function Description
ncGetDriverAttr gets the value of an attribute in the NI-DNET driver software. Within NI-DNET objects, attributes represent configuration settings, status, and other information.
Since you only need to access NI-DNET driver attributes under special circumstances, ncGetDriverAttr is seldom used. For information about the attributes of each NI-DNET object, refer to NI-DNET Objects.
ncGetDriverAttr only applies to the NI-DNET software on your computer and cannot be used to get an attribute from a remote DeviceNet device. To get an attribute from a remote DeviceNet device, use the ncGetDnetAttribute function.
Parameter Descriptions
ObjHandle
| Description | ObjHandle must contain an object handle returned from ncOpenDnetExplMsg, ncOpenDnetIntf, or ncOpenDnetIO. In LabVIEW, ObjHandle passes through the VI as an output so that it can be used for subsequent function calls for the object. |
| Values | The encoding of ObjHandle is internal to NI-DNET. |
AttrId
| Description | Identifier of the NI-DNET attribute. Supported attribute identifiers for each NI-DNET object are listed in NI-DNET Objects. |
| Values | 80000000 to 8000FFFF hex (high bit differentiates from DeviceNet IDs) |
SizeofAttr
| Description | For C, this is the size of the buffer referenced by Attr. It is used to verify that you have enough bytes available to store the attribute's value. This size is normally obtained using the C language sizeof function. For LabVIEW, since the buffer for Attr is allocated automatically by NI-DNET, this size is not needed. |
| Values | sizeof (buffer referenced by Attr) |
Attr
| Description | Returned attribute value. The value is usually returned in an unsigned 32-bit integer (and thus Attr is of type NCTYPE_UINT32_P). |
| Values | Value of NI-DNET attribute |
Examples
LabVIEW
Get the DeviceNet protocol version supported by NI-DNET.
C
Get the version of the NI-DNET software using the Interface Object referenced by objh.
NCTYPE_STATUS status;
NCTYPE_OBJH objh;
NCTYPE_VERSION swver;
status = ncGetDriverAttr(objh, NC_ATTR_SOFTWARE_VERSION,
sizeof(swver), &swver);