Retrieving weights from scales to excel - vba

Question

I have connected a weighing scale to my PC via an RS-232 to USB converter cable. My goal was to create a command button in excel 2007 that would place the weight from the scale into the selected cell. I got it to work using the following code in a userform.
Private Sub XMCommCRC1_OnComm()
Static sInput As String
Dim sTerminator As String
Dim Buffer As Variant
' Branch according to the CommEvent property
Select Case XMCommCRC1.CommEvent
Case XMCOMM_EV_RECEIVE
Buffer = XMCommCRC1.InputData ' Use Input property for MSComm
sInput = sInput & Buffer
If Worksheets("Settings").Range("Terminator") = "CR/LF" Then
sTerminator = vbCrLf
Else
sTerminator = vbCr
End If
If Right$(sInput, Len(sTerminator)) = sTerminator Then
XMCommCRC1.PortOpen = False
sInput = Left$(sInput, Len(sInput) - Len(sTerminator))
Select Case Left$(sInput, 2)
Case "ST", "S "
ActiveCell.Value = CDbl(Mid$(sInput, 7, 8))
ActiveCell.Activate
Case "US", "SD"
MsgBox "The balance is unstable."
Case "OL", "SI"
MsgBox "The balance is showing an eror value."
End Select
sInput = ""
End If
End Select
End Sub
Public Sub RequestBalanceData()
With Worksheets("Settings")
' Configure and open the COM port
If Not XMCommCRC1.PortOpen Then
XMCommCRC1.RThreshold = 1
XMCommCRC1.RTSEnable = True
XMCommCRC1.CommPort = .Range("COM_Port")
XMCommCRC1.Settings = .Range("Baud_Rate") & "," & _
.Range("Parity") & "," & _
.Range("Data_Bits") & "," & _
.Range("Stop_Bits")
XMCommCRC1.PortOpen = True
End If
' Send balance's "SI" (Send Immediate) command
' to request weighing data immediately
If .Range("Terminator") = "CR/LF" Then
XMCommCRC1.Output = "R" & vbCrLf
Else
XMCommCRC1.Output = "R" & vbCr
End If
End With
End Sub
I then created a command button with the following code.
Private Sub CommandButton1_Click()
UserForm1.RequestBalanceData
End Sub
When I click on the command button the weight is placed in the selected cell. However, this does not consistently happen. Sometimes when I click the button nothing will be placed in the cell, and I will have to click it multiple times until the weight is placed in the cell. I would like to fix this, but I'm not sure where to start. Is it a problem with the code itself, or is it more likely a problem with the converter or the scale itself?
Any help is appreciated.
Here is the scale: https://www.optimascale.com/product-page/op-915-bench-scale
Here is the converter cable: https://www.amazon.com/gp/product/B06XJZHCV8/ref=ox_sc_act_title_3?smid=A33N7O64F8FSDL&psc=1
Here is the tutorial I used for the code: http://www.msc-lims.com/lims/diybalance.html
Here is the ActiveX control from the tutorial that I used: http://www.hardandsoftware.net/xmcomm.htm
EDIT: I have done what Wedge has suggested and placed a Mgsbox sInput after my first End If. I have been getting inconsistent results. I am wondering if I need to change my scales sending format. The scale is currently set to sending format 4.
Here is the scale manual (sending formats are on page 21-23: https://docs.wixstatic.com/ugd/78eff6_e629ae5fe7004c7189060cca4bc7c3de.pdf
2ND EDIT:
I have connected my serial port to putty. My scale is in continuos sending mode. In putty the scale is consistently sending the following: ST,GS+ 0.00lb. However, when i try to enter the weight value in a cell, the message box sometimes displays that part of the data sent (ST,GS+ 0.00lb) has got cut off, or has been sent multiple times with one button press. Does anyone know how I would fix this?
3RD EDIT: It seems to me that the continuous sending mode (mode 4) my scale is set to is sending data too fast and is causing my code to mess up. I would like to try to make this work with the command request mode (mode 3), but I can't figure out how to properly parse the data string and place it into a cell. The sending format for command request mode is :
If anybody could help me figure out how to get this working I would greatly appreciate it.