naj.keclv

GX Works 2 + FX3U array of sdt & fb in another fb

6 posts in this topic

Posted (edited)

Hello everybody,

i have some uncertainties going through my head. i am fairly new in PLC word, graduated last year, last 12 month i did project on Siemens PLCs, but now i have to expand my view with Mitsubishi.

1.

i am working on project with several conveyors. for each conveyor type i have FB fairly similar to my FB in siemens. For all conveyor i am using same sdt containing 32 bits. So a have array[0..20]  of said sdt. But in fb i was not able to copy item from array, through input var containing index of that item to vocal variable, which i wanted to write back to the array at the end of fb. I tried different approach ->  using item from array *** input/output.  When monitoring item from array i can see, that variables i change in got2000 panel are in fact changing. But when i monitor fb itself, those same variables are not changing.

i reworked this fb several times, for example when i found out that FB variables FB FXcpu cannot be set as retain so i would like to use it and i see no other way than make this fb work. :D

2. Is there possibility to us FB in another FB? I remember that i read some restriction about this, but now, i cannot find it.

Thank you everybody for your responses

 

 

Edited by naj.keclv
more specific title

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1.  Can you attach a small example project. then we can take a look at where you are going wrong.

2. Yes it is possible to use a FB in a FB in a FB etc, If you want to use a label from inside a FB just use the nameFB.nameFB.labelname

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Hello again,

so as in/out i use db_MVT[2] (it is 32 bit) cyan blue in first picture, and variable HS_L of db_mvt[2] is currently logic 1. But in function block it does not reflect. As when i monitor fb with correct insatance it shows logic 0.

Screenshot 2021-04-09 093819.png

Screenshot 2021-04-09 093902.png

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strange, but it is defined as an inout. could it be that it is reset in the FB itself ?

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no, the variable is only used as read. But i might delete array of sdt and replace it with several sdts. Because i do not have good experience with arrays and gx works 2. :D and those two for loops i will just rewrite manually as the array itself is not that big, only twenty elements. or i will use of index registers.

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So apparently, gx works 2 cannot handle an instance of array as an input to function block.

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