IF... THEN... ELSE syntax help needed.

searthur

I’m looking for some help on the “IF… THEN… ELSE” syntax. I’m trying to look at the status of three input pins and then change some output pins if a certain condition exists. Below is my source file. Can anyone tell me what I’m doing wrong?


Main:
IF IN5=0 THEN GPOHI
ELSEIF
IN6=0 THEN GPOHI
ELSEIF
IN7=1 THEN GPOHI
ELSE GPOLO
ENDIF
GOTO Main
END

GPOHI:
HIGH 15 'Energize relay 1
HIGH 14 'Energize relay 2
HIGH 13 'Energize relay 3
GOTO Main

GPOLO:
LOW 15 'Relax relay 1
LOW 14 'Relax relay 2
LOW 13 'Relax relay 3
GOTO Main

erco

Looks good. You are using PBASIC 2.5, not 2.0?

searthur

I'm running 2.5.2 When I do a syntax check I get "expected ":" or end-of-line error just after the IN6=0. So is it ok to have more than one ELSEIF like I'm trying to do above?

erco

IF IN6=0

IF IN7=1

You left out two IF statements.

Ron Czapala

I generally avoid ELSEIF, but try:

' {$STAMP BS2}
' {$PBASIC 2.5}
Main:
IF (IN5=0) THEN
  GOTO GPOHI
ELSEIF(IN6=0) THEN
  GOTO GPOHI
ELSEIF (IN7=1) THEN
  GOTO GPOHI
ELSE
  GOTO GPOLO
ENDIF
GOTO Main
END

GPOHI:
 HIGH 15 'Energize relay 1
 HIGH 14 'Energize relay 2
 HIGH 13 'Energize relay 3
 GOTO Main

GPOLO:
 LOW 15 'Relax relay 1
 LOW 14 'Relax relay 2
 LOW 13 'Relax relay 3
 GOTO Main

erco

Main:
IF IN5=0 THEN GPOHI
IF IN6=0 THEN GPOHI
IF IN7=1 THEN GPOHI
GOTO GPOLO

or:

Main:
IF IN5=0 OR IN6=0 OR IN7=1 THEN GPOHI
GOTO GPOLO

Tracy Allen

That particular condition could be written

IF IN5=0 OR IN6=0 OR IN7=1 THEN GOTO GPOHI ELSE GOTO GPOLO

searthur

I get "label already defined" at the second ELSEIF...

searthur

I get "expected a label" after the "THEN" statement.

searthur

What about this (see below). It passes the syntax check and I think will do the same thing.

Main:
IF IN5=0 THEN GPOHI
IF IN6=0 THEN GPOHI
IF IN7=1 THEN GPOHI
GOSUB GPOLO
GOTO Main
END

'******************************************************************[ Subroutines ]
'
GPOHI:
HIGH 15 'Energize relay 1
HIGH 14 'Energize relay 2
HIGH 13 'Energize relay 3
GOTO Main

GPOLO:
LOW 15 'Relax relay 1
LOW 14 'Relax relay 2
LOW 13 'Relax relay 3
RETURN
GOTO Main

erco

Sure, that subroutine works, too. You don't need your END or final GOTO MAIN statement, as they'll never execute.

Ron Czapala

Make sure you have the

' {$PBASIC 2.5}

statement if you want to use 2.5

searthur

Thanks erco. This seems to work nicely (see below).

Main:
IF IN5=0 OR IN6=0 OR IN7=1 THEN GPOHI
GOTO GPOLO



GPOHI:
HIGH 15 'Energize relay 1
HIGH 14 'Energize relay 2
HIGH 13 'Energize relay 3
GOTO Main

GPOLO:
LOW 15 'Relax relay 1
LOW 14 'Relax relay 2
LOW 13 'Relax relay 3
GOTO Main

searthur

Thank you everyone for all the assistance. I really appreciate it.