CLS: CLEAR
DIM inbuf(800)
DIM outbuf(8)
OPEN "com2:19200,n,8,1,bin,cs,ds" FOR RANDOM AS #1
 
'--INTERRUPT SERIAL INTERFACE ON---
COM(2) ON
ON ERROR GOTO BADCOM
ON COM(2) GOSUB GETFRAME
 
'---INITIALIZE RELAIS BOARD---
PRINT "INITIALIZE BOARD"
outbuf(0) = 1: outbuf(1) = 1: outbuf(2) = 0: GOSUB sendframe
 
FOR delay = 1 TO 1000000:NEXT:CLS
 
'SWITCH RELAIS
teststart:
r = 1
rt:
outbuf(0) = 3: outbuf(1) = 1: outbuf(2) = r: GOSUB sendframe
FOR delay = 1 TO 1000000: NEXT:CLS
r = r * 2: IF r < 256 THEN GOTO rt
GOTO teststart
 
'Serial Communication
'
'READ 4 BYTE DATAFRAME
'
GETFRAME:
inbuf(bz) = ASC(INPUT$(1, #1))
bz = bz +1
IF bz = 4 THEN GOTO checkframe
RETURN
'CHECK VALIDITY
chechframe:
ERROR$="ERROR"
IF inbuf(0) xor inbuf(1) xor inbuf(2) = inbuf(3) THEN
ERROR$ = "OK"
bz = 0: PRINT "RECEIVED:";"    ";inbuf(0);"   ";inbuf(1);"";inbuf(2);"  " & _
  "";inbuf(3);" ";ERROR$
PRINT"-------------------------------------------------------------":RETURN
'-----------------
 
'SEND 4 BYTE DATAFRAME
 
sendframe:
outbuf(3) = outbuf(0) xor outbuf(1) xor outbuf(2)
send$ = CHR$(outbuf(0)) + CHR$(outbuf(1)) + CHR$(outbuf(2)) + CHR$(outbuf(3))
PRINT #1, send$
PRINT "TRANSMITTED:";"   ";outbuf(0);"    ";outbuf(1);"   ";outbuf(2); "   " & _
  "";outbuf(3)
RETURN
 
'ERROR HANDLER
BADCOM:
PRINT "--DATA ERROR---"
 RESUME
RETURN
 
ende:
END