Campbell Scientific 0871LH1 Freezing Rain Sensor - Manual (Page 17)

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'update the byte count
Old_Byte_Count = LH1_Byte_Count
'reset and start the timer
Timer (1,mSec,2)
'Received at least one byte start checking for a blank time
CheckForBlankTime = True
EndIf
'Obtain the time from the last byte.
TimeSinceLastByte = Timer (1,mSec,4)
If CheckForBlankTime = True Then
'If no characters occur within 100 msec of last byte then assume end of packet.
If TimeSinceLastByte > 100 Then Stay_In_Loop = False
EndIf
'Exit regardless if more than 3 seconds elapse
If TimeSinceLastByte > 3000 Then
LH1_Serial_Error = True
Stay_In_Loop = False
EndIf
Wend
If LH1_Serial_Error = False Then
'Flush the buffer
SerialFlush (LH1_comport)
'Wait a mximum of 2 seconds
If Timer (2,mSec,4) > 2000 Then
LH1_Serial_Error = TRUE
Stay_In_Loop = False
EndIf
Wend
'Obtain a CheckSum and convert All Binary Values
LH1_CHECKSUM = 0
'Convert all the BINARY Values
For LoopCounter=1 To 24 Step 1
LH1_Byte(LoopCounter) = ASCII (LH1_Raw_In_Buff(1,1,LoopCounter))
If LoopCounter <> 24
LH1_CHECKSUM = LH1_CHECKSUM + LH1_Byte(LoopCounter)
EndIf
Next
LH1_CHECKSUM = LH1_CHECKSUM AND &B11111111
If LH1_CHECKSUM <> LH1_Byte(LoopCounter) Then LH1_Serial_Error = TRUE
EndIf
If LH1_Serial_Error = TRUE Then
Call LH1_Error_State
Else
'For LH1 Byte 1
'BIT 0 - Status Output
If (LH1_Byte(1) AND &B00000001) <> 0 Then
LH1_Status_Output = "Fail"
Else
LH1_Status_Output = "OK"
EndIf