功能明细 > 数据接口 > COM接口 > VB 接口 > 查询实时记录（单点查询）com_sn_query

函数

STDMETHOD(com_sn_query_snapshot)(

LONGnTagID,

VARIANT* nSec,

VARIANT* nMsec,

VARIANT* nQuality,

VARIANT* nTagType,

VARIANT* bsValue,

LONG* nRetErr

);

参数

[in]LONGnTagID, TagID

[out]VARIANT* nSec, 实时记录的秒，nSec->vt = VT_I4

[out]VARIANT* nMsec, 实时记录的毫秒，nMsec->vt = VT_I4

[out]VARIANT* nQuality,实时记录的数据质量，nQuality->vt = VT_I4

[out]VARIANT* nTagType, 实时记录的Tag类型，nTagType->vt = VT_I4

[out]VARIANT* bsValue, 实时记录的值，bsValue->vt = VT_BSTR

[out,retval]LONG* nRetErr返回值

返回值

成功，返回RD_SUCCESS。失败返回其它错误码，见error_code.h

说明

查询实时记录（单点查询）函数。该函数用来查询一个Tag保存在内存快照中的最新记录。返回的实时记录的值用字符串的形式表示。

举例

Set objArray= CreateObject("hdCOMInterface.hdCOMClass.1")

Dim ip,port,bakip,bakport,timeout

ip= "127.0.0.1"

port= 5678

bakip = "1.2.3.4"

bakport = 1234

timeout= 3

Dim ret

objArray.com_nt_connect ip,port,bakip,bakport,timeout

Dim id,result

id=5

Dim nsec,nmsec,nquality,ntype,nvalue

result = CLng(objArray.com_sn_query_snapshot(id,nsec,nmsec,nquality,ntype,nvalue))

Msgbox "com_sn_query_snapshot错误码是：" &result

if result=0 then

Msgbox "sec is:" &nsec

Msgbox "msec is:" &nmsec

Msgbox "quality is:" &nquality

Msgbox "type is:" &ntype

Msgbox "value is:" &nvalue

end if

objArray.com_nt_disconnect

Set objArray= nothing

查询实时记录（单点查询）com_sn_query_snapshot