Why does this LotusScript halt during a loop? - user-interface

Question

I am trying to write a LotusScript to control a motor. The script I have for reading the bits seem to work fine, but I wish to add a stop button. I have all the commands for making the device stop, but the trouble I'm having is that whenever LotusScript is running through a loop, I cannot click on any of the other buttons.
Does anyone know a way around this???
The scripts I am using are below.
Thank-you kindly.
Andy Barlow
Sub readpositionsub
Dim send_string As String
Dim readString As String
Dim tempString As String
readString = ""
REM Sets the "movement" cell to 6 (the movement int)
[b1].contents = "6"
Do While [b1].contents <> "7"
readString = ""
statusBitString = ""
REM READ STATUS ===!!!===
REM Open the handle to the motor
handle = init_RS232(19200)
REM #1$ reads the status from the controller.
send_string = "#1$"+Chr$(13)
REM Ask the controller to store the results in bits
resultStatus=write_RS232 (handle,send_string)
REM Read Status by looping through all of the bits
For n=0 To 8
tempString = "*1234567"
sendReadCommand = read_RS232(handle,tempString)
If Mid(tempString,1,1) = Chr$(13) Then
Exit For
Else
statusBitString = statusBitString + Mid(tempString,1,1)
End If
Next
[b1].contents = Mid(statusBitString,7, 1)
close_RS232(handle)
REM End Read Status
REM READ POSITION ===!!!===
REM Open the handle to the motor
handle = init_RS232(19200)
send_string = "#1C"+Chr$(13)
t=write_RS232 (handle,send_string)
REM Reading Position
For n=0 To 20
tempString = "*1234567"
r = read_RS232(handle,tempString)
If Mid(tempString,1,1) = Chr$(13) Then
Exit For
Else
readString = readString + Mid(tempString,1,1)
End If
Next
REM End Read Position
[a1].contents=Mid(readString, 4)
close_RS232(handle)
Loop
End Sub
And the stop button that should work should be...
Object btnStop
Sub Click(Source As Buttoncontrol)
REM initialise
handle = init_RS232(19200)
REM Create the string for starting the motor
send_string = "#1S"+Chr$(13)
REM Send the string for starting the motor
resultStartMotor=write_RS232 (handle,send_string)
REM Close the spin handle
close_RS232(handle)
End Sub

Answer 1

You're not running your Lotusscript in a threaded environment, so how do you expect the code on a button to stop the code already running?

Answer 2

If you want to be able to cancel a loop you need to play with the timer object. Basically you start a time that executes one iteration of your loop. At the beginning you look for a changed field value or an ini variable to cancel the timer if set. Now you can use your button to set that variable.
The loop will run much slower than without a timer (after all it has a wait interval you set)