A-14 | Thermox TM 2000 Oxygen Analyzer
Sample Program
This section provides a sample Quick Basic program that reads and writes
to the serial port:
DECLARE FUNCTION Checksum$ (M$)
‘Serial test routine
‘ Continuously sends a message and prints the string returned
CLS
‘Open the communications port
OPEN “COM2:9600,N,8,1 “FOR RANDOM AS #1
‘String to be echoed
T$ = “Test message”
‘Address of the series 2000 controller
Address% = 254
‘Build the message
M$ = “>” = HEX$(Address%) = “A” = T$
M$ = M$ + Checksum$(M$)
‘Continue sending message until key pressed
‘(Assumes that Series 2000 controller is connected)
WHILE (INKEY$ = “”)
PRINT #1, M$
LINE INPUT #1, A$
‘Show results
PRINT “Sent…..”; M$
PRINT “Returned…”; A$
PRINT
WEND
CLOSE #1
STOP
FUNCTION Checksum$ (M$)
DIM Sum AS LONG
Sum = 0
‘Skip >
FOR I% = 2 TO LEN(M$)
Sum = Sum + ASC(MID$(M$, i%,1)
NEXT I%
‘Get low byte of checksum
Checksum$ = HEX$(Sum MOD 256)
END FUNCTION
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