Old classic If-Then...

I got a little confussed on this nested If-Then:

Code:

---


if level<=high_level then
        if thermiko1=0 then
                if thermistor1=0 then
                        if auto1=0 then
                                if onboard_an2<=pres_limit then
                                        if pump=0 then
                                                module_rel_out=1
                                        else
                                                module_rel_out=0
                                        endif
                                endif
                        endif
                endif
        endif
endif

---

does make module_rel_out=1 but does not makes it 0 if the conditions (one or more) are not met.

I am missing something but cannot figure what...

Any help appreciated.
Ioannis

You need to insert the ELSE statement for each IF. For example, if the first IF is not true, the code never gets to the ELSE ...=0

to execute this part...

Code:

---

if pump=0 then
                                                module_rel_out=1
                                        else
                                                module_rel_out=0
                                        endif

---

ALL previous conditions have to be met.

Simply pre-load the ELSE condition into the variable before entering the IF loop...

Code:

---

module_rel_out=0
if level<=high_level then
        if thermiko1=0 then
                if thermistor1=0 then
                        if auto1=0 then
                                if onboard_an2<=pres_limit then
                                        if pump=0 then module_rel_out=1
                                        endif
                                endif
                        endif
                endif
        endif

---

Hi, Ioannis

Why not use an AND combination of your conditions.

Karnaugh would LOVE your example.

Try this little soft ... and ENJOY.

Karnaugh Minimizer 2.0
Copyright (c) 2002-2007 ShurikSoft.
http://www.shuriksoft.com

Alain

Hi all and thanks for the replies.

Alain: I tried with AND but got an error of too many variables. Indeed was long line!

Melanie: That was what I did just before reading your post. Yes this works but was not appealing to me as an elegant solution.

Steve & Tobias: Yes,I see now, after the morning cup of coffee that it never reached the ELSE statement.

Thanks again to all.

Ioannis

Hi Ioannis

I do not Understand you ...

Code:

---


'Essai 16F84 Random

DEFINE LCD_EBIT 1                          ' Other LCD pins are same as Manual - Holy Manual - my sweet Manual ...

'  DEFINE LCD_DREG PORTB              ' I/O port where LCD is connected
'  DEFINE LCD_DBIT 0
'  DEFINE LCD_RSREG PORTB
'  DEFINE LCD_RSBIT 4                  ' Register select pin
'  DEFINE LCD_EREG PORTB
'  DEFINE LCD_EBIT 5                  ' Enable pin
'  DEFINE LCD_BITS 4                  ' 4-bit data bus
'  DEFINE LCD_LINES 2                  ' LCD has 2 character lines
 
  DEFINE OSC 4
 
@        __config _XT_OSC & _WDT_ON & _CP_OFF

'*****************************************************************************
'Variables

Level                            var Word
High_Level                var Word

Onboard_an2                var Word
PressLimit                var Word

Auto1                        var Bit
Thermikol                var Bit
Thermistor1                var Bit
Pump                        var Bit

LevelOk                        var Bit
PressOk                        var Bit

module_rel_out        var Portb.7

'*****************************************************************************
'Constantes

'*****************************************************************************
'Preset

CLEAR

PORTA = 0
PORTB = 0

TRISA = 0
TRISB = 0

High_Level        = 40000
Level                = 0
Thermikol  = 1
Thermistor1        = 1
Onboard_an2 = 500
PressLimit        = 35000

Auto1                = 1
Pump                = 0



PAUSE 500

LCDOUT $FE,1

RANDOM Level
RANDOM Onboard_An2

Loop:

RANDOM Level
RANDOM Onboard_An2

IF (level <= high_Level) THEN
        PORTB.5 = 1
ELSE
          PORTB.5 = 0
ENDIF

IF ( onboard_an2 <= PressLimit ) THEN
        PORTB.6 = 1
ELSE
          PORTB.6 = 0
ENDIF

Module_rel_out =  (level <= high_Level) && Thermikol && Thermistor1 && Auto1 && ( onboard_an2 <= PressLimit ) && !Pump 

LCDOUT $FE,2,# Module_Rel_Out ,"  ",DEC5 Level ," ",DEC5 Onboard_an2 ,"  "
LCDOUT $FE,$C0,"out", DEC5 High_Level, " ", DEC5 Presslimit

PAUSE 300

IF Module_rel_out THEN PAUSE 500

GOTO Loop

END

---

As you see ... I played somewhat with my Personnal Testboard to verify everything was running fine ...

And it runs fine !!!

"your" line is here :

Code:

---

Module_rel_out =  (level <= high_Level) && Thermikol && Thermistor1 && Auto1 && ( onboard_an2 <= PressLimit ) && !Pump

---

...

Value Comparisons or logic levels have equal behaviour here ...

Cheers ...

Alain

Hi Alain.

On the following if I try to put the second if-then inside the logic expression, I get an "Temp variables exceeding T4" error in MPASM assembler.

This compiles OK:

Code:

---

if pump=0 and (thermistor1=1 or thermiko1=1 or onboard_an2>(pres_limit+10)) then
        module_rel_out.0=0
endif


if level>stop_level then
        if pump=0 then
                module_rel_out.0=0
        endif
endif

---

This produces the above error:

Code:

---

if pump=0 and (thermistor1=1 or thermiko1=1 or onboard_an2>(pres_limit+10) or level>stop_level) then
        module_rel_out.0=0
endif

---

Thanks,
Ioannis

Hi, Ioannis

Do not use " IF thermistor1 = 1" but "IF Thermistor" ... result is the same

Do not use " IF thermistor1 = 0 " but "IF NOT Thermistor" ... result is the same

Alain

Code:

---

if  (pump=0) and ( thermistor1 or thermiko1 or ( onboard_an2>(pres_limit + 10))) then
        module_rel_out.0=0
endif


if (level>stop_level) then
        if pump=0 then
                module_rel_out.0=0
        endif
endif

---

Compile fine

BUUUUUUT ... I do think you should make your Karnaugh Table ( Table of states ) "a bit" clearer ... might help a lot ( lol )

Alain

Alain

Thanks Alain,
For

Code:

---

RANDOM Level
RANDOM Onboard_An2

---

It gives me a new test tool, never could see a use for that command before. Sometimes it's not the main point of your posting that benefits others, sometimes it's the little things that you use everyday.

Quote:

---

Originally Posted by Acetronics

Hi, Ioannis

Do not use " IF thermistor1 = 1" but "IF Thermistor" ... result is the same

Do not use " IF thermistor1 = 0 " but "IF NOT Thermistor" ... result is the same

Alain

---

Could you please explain a little more, so I can understand why ?
Thank You

I understand why.. the problem is to explain... enjoy the following language barrier mess :D

If ConditionIsTrue Then DoSomething

Dealing with Bit Var, you have ONLY 2 choices... OR the var is 1 OR the var 0, True or False.

So why messing with condition if your variable already hold it?

It's just another way to write your IF-THEN

Quote:

---

Originally Posted by Ioannis

I get an "Temp variables exceeding T4" error in MPASM assembler.

---

Hi Ioannis,

That error is comming from ReEnterPBP.bas

There's no way for it to know if the complex formula/IF statement is in the main program or the interrupt handler. And if it's in the handler, it will end up overwriting PBP's system vars.

If you know for sure that the offending statements are NOT in the handler. You can open the ReEnterPBP.bas file and comment the error line.

Code:

---

        ifdef T5
;            ERROR "Temp variables exceeding T4"
        endif

---

HTH,

Quote:

---

Originally Posted by Darrel Taylor

Hi Ioannis,

That error is comming from ReEnterPBP.bas

There's no way for it to know if the complex formula/IF statement is in the main program or the interrupt handler. And if it's in the handler, it will end up overwriting PBP's system vars.

If you know for sure that the offending statements are NOT in the handler. You can open the ReEnterPBP.bas file and comment the error line.

Code:

---

        ifdef T5
;            ERROR "Temp variables exceeding T4"
        endif

---

HTH,

---

Hi Darrel,
So if I understand this right, ERROR is a reserved word in assembler, and if IFDEF calls it then MPASM displays the error when compiling . . . YES?<br><br> Hi Steve, thanks , I will give that some thought.

Quote:

---

Originally Posted by Joe S.

Hi Darrel,
So if I understand this right, ERROR is a reserved word in assembler, and if IFDEF calls it then MPASM displays the error when compiling . . . YES?

---

Yup. You got it. :)

Hi. Thanks for the replies.

Alain: I was going to use the syntax later (if thermistor then...), after I had my program working. But as Darrel explained, this would have no effect as the error was coming from the ReEnterPBP.bas.

Darrel: Thanks for the explanation. I forgot to mention that I was using yours routine for the Interupts, sorry... But did not imagine that this could be coming from the ReEnterPBP.bas. It seemed more logical to be a problem of the Assembler or Compiler.

Useful the tip for the error.

Anyway, many thanks to all.

Ioannis