Melfa Basic VI - If...Then...Elseif...Endif Syntax Help / Examples

    I have a simple syntax question concerning Melfa Basic VI If...Then...Elsif...Endif statements.

    What I want this routine to do is this - Based on the exteranl inputs run specific subroutine and if none are true goto a holding Position (posXXX).

    The way I currently have it programmed is working except for when none of the Inputs are true, The program goes to the next subroutine.

    *Box1, *Box2, *Box3 are subroutines. posXXX is the default/ holding position.

    If M_In(11) = 1 Then *Box1

    If M_In(12) = 1 Then *Box2

    If M_In(13) = 1 Then *Box3

    I have read all the Mitsubishi documentation on thes If/Then/Elseif statements and every time I try to include the last "Else" condition I get syntax errors.

    Any help is appreciated, program examples welcome.

    Thanks in advance.

  • Go to Best Answer

    Without knowing Melfa Basic, somethink like this should work:

    it would be better:

    1. posting one of your faulty trials

    2. posting a bit more of your code, at least some lines following the If/Then/Else . :winking_face:

    • Best Answer

    Goto is suboptimal. Make a local subroutine and use GoSub.

    When the subroutine is finished, the program pointer jumps back to the place where it was called.

    Thank you all for your responses.

    BO,

    The script you have is exactly how I have been keeping this process moving fwd.

    But I know there is a more standard way to write this routine. I just kept hitting syntax errors.

    HE,

    I had tried your idea and still received syntax errors.

    Roland,

    Your idea worked great! Below is the working program.

    *BoxEval

    Mvs posPostScan

    If M_In(10) = 1 Then

    GoSub *Box6

    Break

    ElseIf M_In(11) = 1 Then

    GoSub *Box1

    Break

    ElseIf M_In(12) = 1 Then

    GoSub *Box2

    Break

    ElseIf M_In(13) = 1 Then

    GoSub *Box3

    Break

    ElseIf M_In(14) = 1 Then

    GoSub *Box4

    Break

    ElseIf M_In(15) = 1 Then

    GoSub *Box5

    Break

    Else

    GoSub *BoxEval

    EndIf

    Roland - "Goto is suboptimal. Make a local subroutine and use GoSub.

    When the subroutine is finished, the program pointer jumps back to the place where it was called."

    I'm a rookie with Melfa Basic and have always used "Go To" instead of "GoSub".

    What are the practical differences between GoTo and GoSub?

    Edited once, last by grandpaPaulie (October 26, 2022 at 11:52 PM).

    Why don't you read whole byte from in8 and use that number as a CASE number in SELECT CASE command?


    M_In8()

    [Function]

    Returns the value of the input signal.

    M_In: Returns a bit.

    M_Inb or M_In8: Returns a byte (8 bits).

    M_Inw or M_In16: Returns a word (16 bits).


    [Format]

    Example) <Numeric Variable>=M_In(<Equation>)

    Example) <Numeric Variable>=M_Inb(<Equation>) or M_In8(<Equation>)

    Example) <Numeric Variable>=M_Inw(<Equation>) or M_In16(<Equation>)


    [Terminology]

    <Numeric Variable> Specifies the numerical variable to assign.

    <Equation> Enter the input signal number.

    (1)CR800-R/Q series

    10000 to 18191: Multi-CPU share device

    716 to 731: Multi-hand input.

    900 to 907: Hand input.

    (2)CR800-D series

    0 to 255: Standard remote inputs.

    716 to 731: Multi-hand input.

    900 to 907: Hand input.

    2000 to 5071: Input signal of PROFIBUS.

    6000 to 8047: Remote input for CC-Link.


    [Reference Program]

    1 M1%=M_In(0) ' M1 will contain the value of the input signal 0 (1 or 0).

    2 M2%=M_Inb(0) ' M2 will contain the 8-bit information starting from input signal 0.

    3 M3%=M_Inb(3) And &H7 ' M3 will contain the 3-bit information starting from input signal 3.

    4 M4%=M_Inw(5) ' M4 will contain the 16-bit information starting from input signal 5.


    [Explanation]

    (1) Returns the status of the input signal.

    (2) M_Inb/M_In8 and M_Inw/M_In16 will return 8- or 16-bit information starting from the specified number.

    (3) Although the signal number can be as large as 32767, only the signal numbers with corresponding hardware will return a valid value. Value for a signal number without corresponding hardware is set as undefined.

    (4) This variable only reads the data.(4) This variable only reads the data.

    Select Case

    [Function]

    Executes one of multiple statement blocks according to the condition expression value.


    [Format]

    Select[] <Condition>

    Case[] <Expression>

    [ <Process> ]

    Break

    Case[] <Expression>

    [ <Process> ]

    Break

    :

    Default

    [ <Process> ]

    Break

    End[] Select

    [Terminology]

    <Condition> Describe a numeric operation expression.

    <Expression> Describe an expression using the following format. The type must be the same as the condition expression.
    *IS <Comparison operator> <Constant>
    *<Constant>
    *<Constant>TO<Constant>

    <Process> Writes any instruction (other than the GoToGoTo instruction) provided by MELFA-BASIC VI.


    [Reference Program]

    1 Select MCNT

    2 M1=10 ' This line is not executed

    3 Case Is <= 10 ' MCNT <=10

    4 Mov P1

    5 Break

    6 Case 11 'MCNT=11 OR MCNT = 12

    6 Case 12

    7 Mov P2

    8 Break

    9 Case 13 To 18 '13 <= MCNT <=18

    10 Mov P4

    11 Break

    12 Default ' Other than the above.

    13 M_Out(10)=1

    14 Break

    15 End Select


    [Explanation]

    1. If the condition matches one of the Case items, the process will be executed until the next Case, Default or End Select. If the case does not match with any of the Case items but Default is described, that block will be executed.

    2. If there is no Default, the program will jump to the step after End Select without processing.

    3. The Select Case and End Select statements must always correspond. If a GoToGoTo instruction forces the program to jump out from a Case block of the Select Case statement, the free memory available for control structure (stack memory) decreases. Thus, if a program is executed continuously, an error will eventually occur.

    4. If an End Select statement that does not correspond to Select Case is executed, an execution error will occur.

    5. It is possible to write While - WEndWhile-WEnd and For-Next within a Case block.

    6. Use "Case IS", when using the comparison operators (<, =, >, etc.) for the "<Expression>".

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