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Hi all,
I have an application with will moving the record and display in the chart by click a button. Does anyone know how make sure the action is asynchronous?What i mean here is how to make sure the next action is going after the action before completely done.
Any tips are welcome.
regards
lswang
Post your code
simplest way is disable the button at the beginning of your code and enable it again at the end.
Hi
Lord Orwell, thanks for your suggestion.And Leinail31, below is my part of code to implement the display chart action when click on button.
Code:Private Sub Plot_QueryChart(action As Integer)
Dim data As Integer, MoveValue As Integer
On Error GoTo errorhandler
If Not QueryRecordSet.EOF Or Not QueryRecordSet.BOF Then
QueryRecordSet.MoveLast
JJ = QueryRecordSet.RecordCount
'**********************load all record*********************
If action = 0 Then
'*****get recordset
If JJ > 60 Then
QueryRecordSet.Move -cTotal_Brecord '***to search record
EmptyRow = 0
'***currentRecord is to calculate how many record should move
'***cTotal_Brecord is const variable
currentRecord = cTotal_Brecord
'***menuMoveFlag aim to disable some menu button
menuMoveFlag False, True
Else
QueryRecordSet.MoveFirst
EmptyRow = cTotal_Brecord - JJ
currentRecord = 0
menuMoveFlag False, False
End If
'*************move previous 1 record*********************
ElseIf action = 1 Then
If currentRecord + cMovePreOne < JJ Then
currentRecord = currentRecord + cMovePreOne
QueryRecordSet.Move -currentRecord
EmptyRow = 0
If currentRecord + cMovePreOne >= JJ Then
menuMoveFlag True, False
Else
menuMoveFlag True, True
End If
End If
'*************move previous page*************************
ElseIf action = 2 Then
If (currentRecord + movePrePage) <= JJ Then
currentRecord = currentRecord + movePrePage
QueryRecordSet.Move -currentRecord
EmptyRow = 0
If (currentRecord + 1) >= JJ Then
menuMoveFlag True, False
Else
menuMoveFlag True, True
End If
Else
currentRecord = JJ - 1
QueryRecordSet.Move -currentRecord
EmptyRow = 0
menuMoveFlag True, False
End If
'***************move next 1 record*************************
ElseIf action = 3 Then
If currentRecord - cMoveNextOne >= cTotal_Brecord Then
currentRecord = currentRecord - cMoveNextOne
QueryRecordSet.Move -currentRecord
EmptyRow = 0
If currentRecord - cMoveNextOne < 60 Then
menuMoveFlag False, True
Else
menuMoveFlag True, True
End If
End If
'**************move next page*****************************
ElseIf action = 4 Then
If currentRecord - moveNextPage >= cTotal_Brecord Then
currentRecord = currentRecord - moveNextPage
QueryRecordSet.Move -currentRecord
EmptyRow = 0
If currentRecord = 60 Then
menuMoveFlag False, True
Else
menuMoveFlag True, True
End If
Else
QueryRecordSet.Move -moveNextPage
currentRecord = moveNextPage
EmptyRow = 0
menuMoveFlag False, True
End If
'**************search record******************************
ElseIf action = 5 Then
'***SearchLocationPiont is the location of record found
'***CurrentToTalPoint is the total record count
If SearchLocationPoint - (CurrentToTalPoint - JJ) > JJ Then Exit Sub
If SearchLocationPoint - (CurrentToTalPoint - JJ) <= JJ Then
currentRecord = SearchLocationPoint - (CurrentToTalPoint - JJ)
If currentRecord < cTotal_Brecord Then '
currentRecord = moveNextPage
QueryRecordSet.Move -cTotal_Brecord
EmptyRow = 0
menuMoveFlag False, True
ElseIf currentRecord > JJ - cTotal_Brecord Then
currentRecord = JJ - 1
QueryRecordSet.Move -currentRecord
EmptyRow = 0
menuMoveFlag True, False
Else
QueryRecordSet.Move -currentRecord
EmptyRow = 0
menuMoveFlag True, True
End If
End If
'*********move to First Page********************************
ElseIf action = 6 Then
currentRecord = JJ - 1
QueryRecordSet.Move -currentRecord
EmptyRow = 0
menuMoveFlag True, False
'********move to Last page*********************************
ElseIf action = 7 Then
'***moveNextPage is a variable
QueryRecordSet.Move -moveNextPage
currentRecord = moveNextPage
EmptyRow = 0
menuMoveFlag False, True
End If
DoEvents
'**************insert data,plot chart************************
For data = 1 To cTotal_Brecord
If data > EmptyRow Then
If Not (QueryRecordSet.BOF) Then
Debug.Print (Format$((QueryRecordSet("RDate")), "dd/mm/yy") & " " & Format$((QueryRecordSet("RTime")), "hh:mm:ss"))
QueryArrValues(data, 1) = Format$((QueryRecordSet("RDate")), "dd/mm/yy") & " " & Format$((QueryRecordSet("RTime")), "hh:mm:ss") ' Labels
QueryArrValues(data, 2) = IIf(IsNull(QueryRecordSet(PreFieldString)), 0, QueryRecordSet(PreFieldString)) ' Series 1 values.
QueryArrValues(data, 3) = IIf(IsNull(QueryRecordSet(ActFieldString)), 0, QueryRecordSet(ActFieldString)) ' Series 2 values.
QueryRecordSet.MoveNext
End If
Else
QueryArrValues(data, 1) = " " ' Labels
QueryArrValues(data, 2) = 0 ' Series 1 values.
QueryArrValues(data, 3) = 0 ' Series 2 values.
End If
Next data
DoEvents
MSChart1.TitleText = trendName & " -- " & trendPreriod
MSChart1.ChartData = QueryArrValues
MSChart1.Column = 1: MSChart1.ColumnLabel = "Pre."
MSChart1.Column = 2: MSChart1.ColumnLabel = "Act."
'*******************************************************************************
End If
Exit Sub
errorhandler:
Call ELogger("Plot_Chart" & "-" & action)
Resume Next
End Sub
You wouldn't have the problem if that doevents was not in there. why is it there?
hi
Actually my whole application are containts 4 timers and will run every 1.5 sec and 5 sec.So, i need to use doevents to release my cpu usage,and avoid lack up of application.Does it make a problem for my application if i put the doevents there?
regards
lswang
yes, but you can cut down on the problems with global variables at the start of each of your subroutines. Set it to a value when your sub starts, and the line before that checkes to see if the value is already set. If so, exit sub/function. Last line of sub (or any place you have an exit sub) you reset the value. This prevents a subroutine from running more than once at the same time.
As for having all of those timers. This is a bad idea. A program never needs more than one. You use counting loops with static variables to ensure that you have the time interval you want. I am positive you are doing this already since you have intervals greater than 100ms. This is the biggest problem. Timers are unreliable and if you have more than one firing at the same time, occasionally (but quite often) you will lose event triggers.
Hi,
Did you mean set a flag before check the recordset and reset the flag?Code:Set it to a value when your sub starts, and the line before that checkes to see if the value is already set. If so, exit sub/function. Last line of sub (or any place you have an exit sub) you reset the value.
I had no choice but have to do it because i need to get some data due com port and at the same time i need to plot the chart according to the value which i got. And yes, as you said, i may be lose the events triggers while the other timers run toghter.Code:As for having all of those timers. This is a bad idea.
Can you please briefly how can i use counting loops to get the intervals time i need in condition that i have 3 action (currently using timers to run the action)need to complete at the same time..
thanks
best regards
lswang
yes it just requires a global variable for each one.
get the picture? You never need more than one timer, and it can be demonstrated pretty easily that as few as 3 or 4 timers will miss events.Code:(inside timer1_timer with interval of 100)
a = a + 1
b = b + 1
c = c + 1
if a = 100 then a = 0: Call CodeThatTriggersEvery10Seconds
if b = 10 then b = 0: Call CodeThatTriggersEverySecond
if c = 450 then c = 0 etc.
end sub
The MSComm control is event-driven, you don't need timers. If you get your incoming data in the MSComm1_OnComm event, the event will fire when there's data to get, regardless of what else you're doing. If you're using a timer to look at MSComm1.Input, you're using the control the wrong way. There's almost never a good reason to poll an interrupting asynchronous input.Quote:
Originally Posted by cocoon_wls
hi,
First,thanks for Loar Orvwell, i have got the pic and then i will try it in my program.So, that mean if i running these code in my application, the percentage of lost event triggers will be decrease,am I right?
Second, for the Al42,thanks for your suggestion.Basically, in my application i already running the concept you are mention, which is get data while the comm event fired.But at the same time i need another timer to get the data and continue my next action if i cant receive the complete data from comm in 100ms.Example,i need to get 10 char from comm in 100ms. If i cant complete get all the data in 100ms, i will give up and continue my next action (in my condition, i cant wait untill i get the complete data, i must move to next action after 100ms).
In theory, it should be more reliable.