Dear Users,

I´m a beginner in Siemens STL code and I would like your help, please.

I have to do ablock (FB or FC - I don´t know which is the better ?)thatpicksup a value (e.g. analog value)from a variable(#MEASURE) every 500ms (supposed time #BS_Tmp) and save into a DB number (#DB_NUM).
Iwrote the code below, but I don´t know how to set a initial value for #count_pointer variable. Any suggestion ?

// Using FB

A #EN // Enable bit
JCN END

L #DB_NUM //Integer defined as IN
T #DB_N
OPN DB [#DB_N] //Interger defined as TEMP

A #Bs_Tmp //Bool defined as IN_OUT
JCN END

L #count_pointer //Integer defined as STAT
SLW 5
LAR1

L #MEASURE //Real defined as IN
T DBD [AR1,P#0.0]

L #count_pointer
INC 1
T #count_pointer

END: NOP 0

Is there another way to write this code using "+AR1P#4.0" instead to use the #count_pointer variable and use a FC block ?

Thanks in advance !

Cheers

Hello Licht,

if you want to store a value in a DB, you need basically a trigger (your BS_temp), when to do it. You also need to know, where to write to:
In your code you have only the DB number, which doesn't help you a whole lot, since you don't know anything about the internal structure of that DB.

At first your statement SLW 5 right before the LAR1 would only allow you to address a limited space inside the DB. Since the AR1 is a 32 bit register you probaly want to use SLD 5 instead of SLW 5.

Second making some assumptions you initial question could be answered easily, when you store the last written address right at the beginning of that DB. In this case you could reuse this information, modify it and store it for later.

Note: try to avoid indirect addressing, when possible. Makes the code easier to understand for everybody. Make sure you evaluate the parameters before using them. Include some range checking to it, like not exceeding the DB boundaries.

Look at the sample

OlafS1

Hello Licht,

if you want to store a value in a DB, you need basically a trigger (your BS_temp), when to do it. You also need to know, where to write to:
In your code you have only the DB number, which doesn't help you a whole lot, since you don't know anything about the internal structure of that DB.

At first your statement SLW 5 right before the LAR1 would only allow you to address a limited space inside the DB. Since the AR1 is a 32 bit register you probaly want to use SLD 5 instead of SLW 5.

Second making some assumptions you initial question could be answered easily, when you store the last written address right at the beginning of that DB. In this case you could reuse this information, modify it and store it for later.

Note: try to avoid indirect addressing, when possible. Makes the code easier to understand for everybody. Make sure you evaluate the parameters before using them. Include some range checking to it, like not exceeding the DB boundaries.

Look at the sample