VB 串口数据采集

实时采集的数据可直接用来画曲线，但往往为了以后查询，同时应按定时间隔写入数据库或文本文件。所以可在写入数据库后通过查询做到实时显示和更新。

'窗体加载时将已记录的数据查询后绘图

Private Sub Form_Load()

chaxun1 = "select from jishijilu where gyh_riqi='" & gongyi_sj(0) & "-" & record_rq & "'order by shijian "

mdh = chaxun1

Adodc3ConnectionString = "Provider=MicrosoftJetOLEDB40;Data Source=C:\Ldgz\wdmdb;Persist Security Info=False"

Adodc3RecordSource = mdh

Adodc3Refresh

zslNew = Adodc3RecordsetRecordCount

Text4 = zslNew

If zslNew >= 1 Then

Adodc3RecordsetMoveFirst

For i = 0 To zslNew - 1

quexian(0, i) = Adodc3Recordset(0)

For j = 2 To 9

quexian(j, i) = Adodc3Recordset(j)

Next j

Adodc3RecordsetMoveNext

Next i

Adodc3RecordsetMoveFirst

For j = 0 To zslNew - 1

Picture1Line (j 5 + 500, quexian(2, j) -30 + 3399)-(j 5 + 500, quexian(2, j) -30 + 3401), vbRed, BF

Picture1Line (j 5 + 500, quexian(3, j) -30 + 3399)-(j 5 + 500, quexian(3, j) -30 + 3401), QBColor(7), BF

Picture1Line (j 5 + 500, quexian(4, j) -30 + 3399)-(j 5 + 500, quexian(4, j) -30 + 3401), vbWhite, BF

Picture1Line (j 5 + 500, quexian(5, j) -30 + 3399)-(j 5 + 500, quexian(5, j) -30 + 3401), vbYellow, BF

Picture1Line (j 5 + 500, quexian(6, j) -30 + 3399)-(j 5 + 500, quexian(6, j) -30 + 3401), vbGreen, BF

If quexian(8, j) < 1 Then

wy_wy = 0 + 1667

br_br = 55

ElseIf quexian(8, j) >= 1 And quexian(8, j) < 10 Then

wy_wy = -1500 + 1667

br_br = 55556

ElseIf quexian(8, j) >= 10 And quexian(8, j) < 100 Then

wy_wy = -3000 + 1667

br_br = 05555

ElseIf quexian(8, j) >= 100 And quexian(8, j) < 1000 Then

wy_wy = -4500 + 1667

br_br = 0055555

End If

Picture1Line (j 5 + 500, quexian(8, j) br_br -30 + wy_wy + 3397 + 3000)-(j 5 + 500, quexian(8, j) br_br -30 + wy_wy + 3403 + 3000), QBColor(11), BF

Next j

zslOld = zslNew

End If

'记录时间最长75小时

Picture2Height = 10000

Picture2Visible = True

Picture1Visible = True

colvb = vbWhite

xx = 100

yy = 150

txt = "℃"

wp = xp(colvb, xx, yy, txt)

yy = 350

txt = "100"

wp = xp(colvb, xx, yy, txt)

xx = 200

yy = 1850

txt = "50"

wp = xp(colvb, xx, yy, txt)

yy = 3350

xx = 300

txt = "0"

wp = xp(colvb, xx, yy, txt)

xx = 100

yy = 4850

txt = "-50"

wp = xp(colvb, xx, yy, txt)

xx = 0

yy = 6350

txt = "-100"

wp = xp(colvb, xx, yy, txt)

xx = 10800 + 100

yy = 150

txt = "℃"

wp = xp(colvb, xx, yy, txt)

yy = 350

txt = "100"

wp = xp(colvb, xx, yy, txt)

xx = 10800 + 200

yy = 1850

txt = "50"

wp = xp(colvb, xx, yy, txt)

yy = 3350

xx = 10800 + 300

txt = "0"

wp = xp(colvb, xx, yy, txt)

xx = 10800 + 100

yy = 4850

txt = "-50"

wp = xp(colvb, xx, yy, txt)

xx = 10800 + 0

yy = 6350

txt = "-100"

wp = xp(colvb, xx, yy, txt)

'真空坐标

colvb = vbRed

xx = 11400

yy = 150

txt = "Pa"

wp = xp(colvb, xx, yy, txt)

yy = 350

txt = "1000"

wp = xp(colvb, xx, yy, txt)

xx = 11500

yy = 1850

txt = "100"

wp = xp(colvb, xx, yy, txt)

yy = 3350

xx = 11600

txt = "10"

wp = xp(colvb, xx, yy, txt)

xx = 11700

yy = 4850

txt = "1"

wp = xp(colvb, xx, yy, txt)

xx = 11500

yy = 6350

txt = "01"

wp = xp(colvb, xx, yy, txt)

xx = 500

yy = 150

txt = "Pa"

wp = xp(colvb, xx, yy, txt)

yy = 350

txt = "1000"

wp = xp(colvb, xx, yy, txt)

yy = 150

xx = 2200

txt = "6hr"

wp = xp(colvb, xx, yy, txt)

xx = 4000

txt = "12hr"

wp = xp(colvb, xx, yy, txt)

xx = 5800

txt = "18hr"

wp = xp(colvb, xx, yy, txt)

xx = 7600

txt = "24hr"

wp = xp(colvb, xx, yy, txt)

xx = 9400

txt = "30hr"

wp = xp(colvb, xx, yy, txt)

xx = 13000

txt = "42hr"

wp = xp(colvb, xx, yy, txt)

xx = 14800

txt = "48hr"

wp = xp(colvb, xx, yy, txt)

xx = 16600

txt = "54hr"

wp = xp(colvb, xx, yy, txt)

xx = 18400

txt = "60hr"

wp = xp(colvb, xx, yy, txt)

xx = 20200

txt = "66hr"

wp = xp(colvb, xx, yy, txt)

xx = 22000

txt = "72hr"

wp = xp(colvb, xx, yy, txt)

xx = 23800

txt = "78hr"

wp = xp(colvb, xx, yy, txt)

xx = 25600

txt = "84hr"

wp = xp(colvb, xx, yy, txt)

xx = 27400

txt = "90hr"

wp = xp(colvb, xx, yy, txt)

xx = 29200

txt = "96hr"

wp = xp(colvb, xx, yy, txt)

xx = 600

yy = 1850

txt = "100"

wp = xp(colvb, xx, yy, txt)

yy = 3350

xx = 11600

txt = "10"

wp = xp(colvb, xx, yy, txt)

xx = 700

yy = 4850

txt = "1"

wp = xp(colvb, xx, yy, txt)

xx = 600

yy = 6350

txt = "01"

wp = xp(colvb, xx, yy, txt)

xx = 22100

yy = 350

txt = "1000"

wp = xp(colvb, xx, yy, txt)

yy = 1850

txt = " 100"

wp = xp(colvb, xx, yy, txt)

yy = 3350

txt = " 10"

wp = xp(colvb, xx, yy, txt)

yy = 4850

txt = " 1"

wp = xp(colvb, xx, yy, txt)

yy = 6350

txt = " 01"

wp = xp(colvb, xx, yy, txt)

'画格

Picture1ForeColor = vbWhite

Picture1Line (450, 700)-(500, 700)

Picture1Line (450, 1000)-(500, 1000)

Picture1Line (450, 1300)-(500, 1300)

Picture1Line (450, 1600)-(500, 1600)

Picture1ForeColor = vbRed

Picture1Line (500, 5667)-(550, 5667)

Picture1Line (500, 7333)-(550, 7333)

Picture1Line (500, 900)-(550, 900)

Picture1Line (500, 10667)-(550, 10667)

Picture1Line (500, 12333)-(550, 12333)

Picture1Line (500, 1400)-(550, 1400)

Picture1Line (500, 15667)-(550, 15667)

Picture1Line (500, 17333)-(550, 17333)

Picture1Line (500, 20667)-(550, 20667)

Picture1Line (500, 22333)-(550, 22333)

Picture1Line (500, 2400)-(550, 2400)

Picture1Line (500, 25667)-(550, 25667)

Picture1Line (500, 27333)-(550, 27333)

Picture1Line (500, 2900)-(550, 2900)

Picture1Line (500, 30667)-(550, 30667)

Picture1Line (500, 32333)-(550, 32333)

Picture1Line (500, 35667)-(550, 35667)

Picture1Line (500, 37333)-(550, 37333)

Picture1Line (500, 3900)-(550, 3900)

Picture1Line (500, 40667)-(550, 40667)

Picture1Line (500, 42333)-(550, 42333)

Picture1Line (500, 4400)-(550, 4400)

Picture1Line (500, 45667)-(550, 45667)

Picture1Line (500, 47333)-(550, 47333)

Picture1Line (500, 50667)-(550, 50667)

Picture1Line (500, 52333)-(550, 52333)

Picture1Line (500, 5400)-(550, 5400)

Picture1Line (500, 55667)-(550, 55667)

Picture1Line (500, 57333)-(550, 57333)

Picture1Line (500, 5900)-(550, 5900)

Picture1Line (500, 60667)-(550, 60667)

Picture1Line (500, 62333)-(550, 62333)

Picture1ForeColor = vbWhite

Picture1Line (450, 400)-(27500, 400)

Picture1Line (450, 1900)-(27500, 1900)

Picture1Line (450, 3400)-(27500, 3400)

Picture1Line (450, 4900)-(27500, 4900)

Picture1Line (450, 6400)-(27500, 6400)

Picture1Line (450, 2200)-(500, 2200)

Picture1Line (450, 2500)-(500, 2500)

Picture1Line (450, 2800)-(500, 2800)

Picture1Line (450, 3100)-(500, 3100)

Picture1Line (450, 3700)-(500, 3700)

Picture1Line (450, 4000)-(500, 4000)

Picture1Line (450, 4300)-(500, 4300)

Picture1Line (450, 4600)-(500, 4600)

Picture1Line (450, 5200)-(500, 5200)

Picture1Line (450, 5500)-(500, 5500)

Picture1Line (450, 5800)-(500, 5800)

Picture1Line (450, 6100)-(500, 6100)

Picture1Line (500, 400)-(500, 6400)

Picture1Line (500 + 0, 400)-(500 + 0, 6400)

Picture1Line (1400 + 0, 400)-(1400 + 0, 6400)

Picture1Line (2300 + 0, 400)-(2300 + 0, 6400)

Picture1Line (3200 + 0, 400)-(3200 + 0, 6400)

Picture1Line (4100 + 0, 400)-(4100 + 0, 6400)

Picture1Line (5000 + 0, 400)-(5000 + 0, 6400)

Picture1Line (5900 + 0, 400)-(5900 + 0, 6400)

Picture1Line (6800 + 0, 400)-(6800 + 0, 6400)

Picture1Line (7700 + 0, 400)-(7700 + 0, 6400)

Picture1Line (8600 + 0, 400)-(8600 + 0, 6400)

Picture1Line (9500 + 0, 400)-(9500 + 0, 6400)

Picture1Line (10400 + 0, 400)-(10400 + 0, 6400)

Picture1Line (11300, 400)-(11300, 6400)

Picture1Line (12200, 400)-(12200, 6400)

Picture1Line (13100, 400)-(13100, 6400)

Picture1Line (14000, 400)-(14000, 6400)

Picture1Line (14900, 400)-(14900, 6400)

Picture1Line (15800, 400)-(15800, 6400)

Picture1Line (16700, 400)-(16700, 6400)

Picture1Line (17600, 400)-(17600, 6400)

Picture1Line (18500, 400)-(18500, 6400)

Picture1Line (19400, 400)-(19400, 6400)

Picture1Line (20300, 400)-(20300, 6400)

Picture1Line (21200, 400)-(21200, 6400)

Picture1Line (22100, 400)-(22100, 6400)

Picture1Line (23000, 400)-(23000, 6400)

Picture1Line (23900, 400)-(23900, 6400)

Picture1Line (24800, 400)-(24800, 6400)

Picture1Line (25700, 400)-(25700, 6400)

Picture1Line (26600, 400)-(26600, 6400)

Picture1Line (27500, 400)-(27500, 6400)

Picture1Line (0 5 + 500, 3400 - b(0) 30)-(c(1) 5 + 500, 3400 - b(0) 30), QBColor(12)

Picture1Line (c(1) 5 + 498, 3400 - b(1) 30)-(c(2) 5 + 502, 3400 - b(1) 30), QBColor(12)

Picture1Line (c(2) 5 + 498, 3400 - b(2) 30)-(c(3) 5 + 502, 3400 - b(2) 30), QBColor(12)

Picture1Line (c(3) 5 + 498, 3400 - b(3) 30)-(c(4) 5 + 502, 3400 - b(3) 30), QBColor(12)

Picture1Line (c(4) 5 + 498, 3400 - b(4) 30)-(c(5) 5 + 502, 3400 - b(4) 30), QBColor(12)

Picture1Line (c(5) 5 + 498, 3400 - b(5) 30)-(c(6) 5 + 502, 3400 - b(5) 30), QBColor(12)

Picture1Line (c(6) 5 + 498, 3400 - b(6) 30)-(c(7) 5 + 502, 3400 - b(6) 30), QBColor(12)

Picture1Line (c(7) 5 + 498, 3400 - b(7) 30)-(c(8) 5 + 502, 3400 - b(7) 30), QBColor(12)

Picture1Line (c(8) 5 + 498, 3400 - b(8) 30)-(c(9) 5 + 502, 3400 - b(8) 30), QBColor(12)

Picture1Line (c(9) 5 + 498, 3400 - b(9) 30)-(c(10) 5 + 502, 3400 - b(9) 30), QBColor(12)

Picture1Line (c(10) 5 + 498, 3400 - b(10) 30)-(c(11) 5 + 502, 3400 - b(10) 30), QBColor(12)

Picture1Line (c(11) 5 + 498, 3400 - b(11) 30)-(c(12) 5 + 502, 3400 - b(11) 30), QBColor(12)

Picture1Line (c(12) 5 + 498, 3400 - b(12) 30)-(c(13) 5 + 502, 3400 - b(12) 30), QBColor(12)

Picture1Line (c(13) 5 + 498, 3400 - b(13) 30)-(c(14) 5 + 502, 3400 - b(13) 30), QBColor(12)

Picture1Line (c(14) 5 + 498, 3400 - b(14) 30)-(c(15) 5 + 502, 3400 - b(14) 30), QBColor(12)

Picture1Line (c(15) 5 + 498, 3400 - b(15) 30)-(c(16) 5 + 502, 3400 - b(15) 30), QBColor(12)

chaxun1 = "select from jishijilu where gyh_riqi='" & gongyi_sj(0) & "-" & record_rq & "'order by shijian "

mdh = chaxun1

Adodc3ConnectionString = "Provider=MicrosoftJetOLEDB40;Data Source=C:\Ldgz\wdmdb;Persist Security Info=False"

Adodc3RecordSource = mdh

Adodc3Refresh

zslNew = Adodc3RecordsetRecordCount

Text4 = zslNew

If zslNew >= 1 Then

Adodc3RecordsetMoveFirst

For i = 0 To zslNew - 1

quexian(0, i) = Adodc3Recordset(0)

For j = 2 To 7

quexian(j, i) = Adodc3Recordset(j)

Next j

Adodc3RecordsetMoveNext

Next i

Adodc3RecordsetMoveFirst

For j = 0 To zslNew - 1

Picture1Line (j 5 + 500, quexian(2, j) -30 + 3399)-(j 5 + 500, quexian(2, j) -30 + 3401), vbRed, BF

Picture1Line (j 5 + 500, quexian(3, j) -30 + 3399)-(j 5 + 500, quexian(3, j) -30 + 3401), QBColor(7), BF

Picture1Line (j 5 + 500, quexian(4, j) -30 + 3399)-(j 5 + 500, quexian(4, j) -30 + 3401), vbWhite, BF

Picture1Line (j 5 + 500, quexian(5, j) -30 + 3399)-(j 5 + 500, quexian(5, j) -30 + 3401), vbYellow, BF

Picture1Line (j 5 + 500, quexian(6, j) -30 + 3399)-(j 5 + 500, quexian(6, j) -30 + 3401), vbGreen, BF

If quexian(8, j) < 1 Then

wy_wy = 0 + 1667

br_br = 55

ElseIf quexian(8, j) >= 1 And quexian(8, j) < 10 Then

wy_wy = -1500 + 1667

br_br = 55556

ElseIf quexian(8, j) >= 10 And quexian(8, j) < 100 Then

wy_wy = -3000 + 1667

br_br = 05555

ElseIf quexian(8, j) >= 100 And quexian(8, j) < 1000 Then

wy_wy = -4500 + 1667

br_br = 0055555

End If

Picture1Line (j 5 + 500, quexian(8, j) br_br -30 + wy_wy + 3397 + 3000)-(j 5 + 500, quexian(8, j) br_br -30 + wy_wy + 3403 + 3000), QBColor(11), BF

Next j

zslOld = zslNew

End If

zslOld = zslNew

End Sub

'通过计时器调用定时更新

Private Sub cmdRef_Click()

chaxun1 = "select from jishijilu where gyh_riqi='" & gongyi_sj(0) & "-" & record_rq & "'order by shijian "

mdh = chaxun1

Adodc3ConnectionString = "Provider=MicrosoftJetOLEDB40;Data Source=C:\Ldgz\wdmdb;Persist Security Info=False"

Adodc3RecordSource = mdh

Adodc3Refresh

zslNew = Adodc3RecordsetRecordCount

Text4 = zslNew

If zslNew > 1 Then

Adodc3RecordsetMoveLast

For j = 2 To 7

quexian(j, i) = Adodc3Recordset(j)

Next j

Picture2Height = 10000

Picture1Visible = True

If zslOld >= 1 Then

For j = zslOld - 1 To zslNew - 1

Picture1Line (j 5 + 500, quexian(2, j) -30 + 3399)-(j 5 + 500, quexian(2, j) -30 + 3401), vbRed, BF

Picture1Line (j 5 + 500, quexian(3, j) -30 + 3399)-(j 5 + 500, quexian(3, j) -30 + 3401), QBColor(7), BF

Picture1Line (j 5 + 500, quexian(4, j) -30 + 3399)-(j 5 + 500, quexian(4, j) -30 + 3401), vbWhite, BF

Picture1Line (j 5 + 500, quexian(5, j) -30 + 3399)-(j 5 + 500, quexian(5, j) -30 + 3401), vbYellow, BF

Picture1Line (j 5 + 500, quexian(6, j) -30 + 3399)-(j 5 + 500, quexian(6, j) -30 + 3401), vbGreen, BF

If quexian(8, j) < 1 Then

wy_wy = 0 + 1667

br_br = 55

ElseIf quexian(8, j) >= 1 And quexian(8, j) < 10 Then

wy_wy = -1500 + 1667

br_br = 55556

ElseIf quexian(8, j) >= 10 And quexian(8, j) < 100 Then

wy_wy = -3000 + 1667

br_br = 05555

ElseIf quexian(8, j) >= 100 And quexian(8, j) < 1000 Then

wy_wy = -4500 + 1667

br_br = 0055555

End If

Picture1Line (j 5 + 500, quexian(8, j) br_br -30 + wy_wy + 3395 + 3000)-(j 5 + 500, quexian(8, j) br_br -30 + wy_wy + 3405 + 3000), QBColor(11), BF

Next j

End If

'记录时间最长96小时

cmdPrintEnabled = True

End If

zslOld = zslNew

End Sub

如果PLC支持RS232 协议 可以用控件mscomm，采取modbus通讯方式；

支持modbus tcp/ip的话 那就可以用winsock 控件

或者现在流行的OPC服务,将plc数据写入OPC服务器 然后通过VB做opc client来实现间接控制

数据接收参考代码:

Private Sub MSComm_OnComm()

Dim bytInput() As Byte

Dim intInputLen As Integer

Select Case frmMainctrMSCommCommEvent

Case comEvReceive

If blnReceiveFlag Then

If Not frmMainctrMSCommPortOpen Then

frmMainctrMSCommCommPort = intPort

frmMainctrMSCommSettings = strSet

frmMainctrMSCommPortOpen = True

End If

'此处添加处理接收的代码

frmMainctrMSCommInputMode = comInputModeText '按ASCII接收

intInputLen = frmMainctrMSCommInBufferCount

ReDim bytInput(intInputLen)

bytInput = frmMainctrMSCommInput

Text1 = bytInput

Text2 = Text1

jscd = Len(Text1)

If Left(Text1, 1) <> Chr(27) Or jscd > 25 Then '

frmMainLabel3BackColor = vbRed

frmMainLabel3ForeColor = vbWhite

frmMainLabel3Caption = "接收信号出错!"

ElseIf Left(Text2, 1) = Chr(27) And Mid(Text2, 25, 1) = Chr(13) Then

frmMainLabel3BackColor = vbGreen

frmMainLabel3ForeColor = vbBlack

frmMainLabel3Caption = "接收信号正常!"

If Left(Text2, 6) = Chr(27) & "R0032" And jscd = 25 Then

If Val(fa2) >= 0 And Len(fa2) = 4 Then

fa2 = "0" & Mid(fa2, 2, 3)

End If

frmMaintxtSend = Chr(27) & fa0 & fa1 & "9999" & zhenkong & fa2 & fa3 & fa4 & Chr(13)

lenTxtSend = Len(txtSend)

frmJishiLabel8Caption = txtSend

frmJishiLabel11Caption = lenTxtSend

If lenTxtSend = 24 Then

Call commFasong

Else

frmMainLabel3BackColor = vbRed

frmMainLabel3ForeColor = vbWhite

frmMainLabel3Caption = "发送信号出错!"

End If

blL1 = Mid$(Text2, 19, 2)

If blL1 = "01" Then

record_jmm(0) = Val(Mid$(Text2, 21, 4)) / 10 '制品1温度

ElseIf blL1 = "02" Then

record_jmm(1) = Val(Mid$(Text2, 21, 4)) / 10 '制品2温度

ElseIf blL1 = "03" Then

record_jmm(2) = Val(Mid$(Text2, 21, 4)) / 10 '制品3温度

ElseIf blL1 = "04" Then

record_jmm(3) = Val(Mid$(Text2, 21, 4)) / 10 '制品4温度

ElseIf blL1 = "05" Then

record_jmm(4) = Val(Mid$(Text2, 21, 4)) / 10 '制品5温度

ElseIf blL1 = "06" Then

record_jmm(5) = Val(Mid$(Text2, 21, 4)) / 10 '制品6温度

End If

record_jm(0) = Val(record_jmm(0))

record_jm(1) = Val(record_jmm(1))

record_jm(2) = Val(record_jmm(2))

record_jm(3) = Val(record_jmm(3))

record_jm(4) = Val(record_jmm(4))

record_jm(5) = Val(record_jmm(5))

blL = Mid$(Text2, 7, 6)

Call Hex_bin '输出口状态鉴别

blLg = Mid$(Text2, 13, 6)

Call hex_bin1 '输出口故障状态鉴别

txtSend = ""

Else

txtSend = ""

End If

End If

If Not blnAutoSendFlag And Not blnReceiveFlag Then

frmMainctrMSCommPortOpen = False

End If

End If

End Select

End Sub

接收的数据按上下位机约定取出赋值于全局变量,在其它窗体进行数据记录(写入数据库)

数据分析通过数据控件及SQL查询语句来完成任务

以下提供MSDN参考：

OnComm 常数

常数 值 描述

comEvSend 1 发送事件。

comEvReceive 2 接收事件。

comEvCTS 3 clear-to-send 线变化。

comEvDSR 4 data-set ready 线变化。

comEvCD 5 carrier detect 线变化。

comEvRing 6 振铃检测。

comEvEOF 7 文件结束。

MSComm 控件提供下列两种处理通讯的方式：

事件驱动通讯是处理串行端口交互作用的一种非常有效的方法。在许多情况下，在事件发生时需要得到通知，例如，在 Carrier Detect (CD) 或 Request To Send (RTS) 线上一个字符到达或一个变化发生时。在这些情况下，可以利用 MSComm 控件的 OnComm 事件捕获并处理这些通讯事件。OnComm 事件还可以检查和处理通讯错误。所有通讯事件和通讯错误的列表，参阅 CommEvent 属性。

在程序的每个关键功能之后，可以通过检查 CommEvent 属性的值来查询事件和错误。如果应用程序较小，并且是自保持的，这种方法可能是更可取的。例如，如果写一个简单的电话拨号程序，则没有必要对每接收一个字符都产生事件，因为唯一等待接收的字符是调制解调器的“确定”响应。

SThreshold 属性

在 MSComm 控件设置 CommEvent 属性为 comEvSend 并产生 OnComm 事件之前，设置并返回传输缓冲区中允许的最小字符数。

说明

若设置 Sthreshold 属性为 0（缺省值），数据传输事件不会产生 OnComm 事件。若设置 Sthreshold 属性为 1，当传输缓冲区完全空时，MSComm 控件产生 OnComm 事件。

如果在传输缓冲区中的字符数小于 value，CommEvent 属性设置为 comEvSend，并产生 OnComm 事件。comEvSend 事件仅当字符数与 Sthreshold 交叉时被激活一次。例如，如果 Sthreshold 等于 5，仅当在输出队列中字符数从 5 降到 4 时，comEvSend 才发生。如果在输出队列中从没有比 Sthreshold 多的字符，comEvSend 事件将绝不会发生。

CommEvent 属性包含实际错误或产生 OnComm 事件的数码。注意，设置 Rthreshold 或 Sthreshold 属性为 0，分别使捕获 comEvReceive 和 comEvSend 事件无效。

另请参阅:

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>

使用定时器控件，在控件内编码！

或者使用Windows api函数

或者使用循环，利用datadiff函数

你可以把下面代码保存为vbs文件：每隔15秒就会出现一个对话框，你可以根据你的需要进行修改！

dim i,dt

dt=now()

i=0

do until i>=20

i=datediff("s",dt,now())

if i>=15 then

msgbox "采集数据"

i=0

dt=now()

end if

loop

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