calling a function block from ST

2020-02-27T21:22:48.886000Z

turns out to be a problem with this specific SD card.

written the config once, but after deletion of this config, unable to acces the SD card from the PLC

rather weird, but worked out with another SD card (borrowed from WAGO; nice guys there!)

calling a function block from ST

2020-02-27T21:22:44.746000Z

this worked it tried...

no errors and it executes..

however I have some specific difficulties with the file open function.
i tried Kurt Braun's example
http://www.youtube.com/watch?v=ovTJ5AZY22g

it fails to open the file on my SD card...

calling a function block from ST

2020-02-27T21:22:43.187000Z

AHA now i notice the error I'm making.

however by looking on the library codesys displays this as a function block.... My mistake.

but still guessing how calling this function is neede I guess something like

sysfileopen(input1, input2).

but if i want to use multiple files, how to do so and how to get the output?
somthing like

OUTPUT := sysfileopen(input1, input2)

so it's like C?

calling a function block from ST

2020-02-27T21:22:39.132000Z

ralph can you please give hin an example?

calling a function block from ST

2020-02-27T21:22:37.667000Z

Hi carcrosser,

SysFileOpen is a function not a funtion block. Means no instance-declaration is needed.

Be carefull most of the system-functions are blocking!

BR
Ralph

calling a function block from ST

2020-02-27T21:22:36.162000Z

I don't see the point in this as input 1 is already a string and the other one is even a static string in the code.

here's the full variable declaration

VAR
   syslog      :   SysFileOpen;
   ssyslogfile      :   STRING;
   sysevent      :   SysFileOpen;
   ssyseventfile   :   STRING;
END_VAR

and the full code

ssyslogffile := CONCAT('S:\',statfilename);
syslog(ssyslogfileile, 'RW');

statfilename is declared globally

   statfilename   : STRING(20)   := 'eatSTAT.csv';

however still suffering same error

calling a function block from ST

2020-02-27T21:22:32.114000Z

there are two problems:
watch how all inputs are declared, in the docs it says string (how long)
same for output
please do not use capital but small letters.

calling a function block from ST

2020-02-27T21:22:30.635000Z

I tried first with a more easy example: the file open function

i tried this one:

   SYSLOG         :   SysFileOpen;

SysFileOpen is a function block from the Syslibfile

however during building I get this error: "Error 3740: INIT (5): unknown type 'SysFileOpen'

in the code I call for the FB like this:

SYSLOG(sSYSLOGFile, 'RW');

This call to function blocks is really freaking me out, feeling so dumb....

PS Paul: ik Took a look at your example, but that's your custom built function block. Mine comes straight out of a library

calling a function block from ST

2020-02-27T21:22:26.565000Z

in the varlist:
function_block:mysql_login;

in the program just press F2
change the blockname from mysql_login to function_block
now all the ins and outs will be in in the program indeed with := and the outputs as =>
you can also use function_block.name. this can also be done with F2 just look in the table under user defined function blocks.

trendmaker.zip [10.55 KiB]

calling a function block from ST

2020-02-27T21:22:24.952000Z

Thknk you for your reply,

however I'm failing to get the declaration in the variable area right. the function block in the library I require is mysql_login
i think for this instance i need to declare something as this function block

so i have to link these 3 options together
MySql_login ("the model" of the function block)
Function_block (the declaration of a function block)
MadeUpName (the variable i'm calling in the POU)

then in the POU i'm able to call MadeUpName("input1", input2, input3 etc)

However I don't even see how i can access the output of this function block. As an ST program is being executed from the top I expect the function block to be executed and straight after the call of this function I can check for success or failure.

Recent posts to calling a function block from ST

calling a function block from ST

calling a function block from ST

calling a function block from ST

calling a function block from ST

calling a function block from ST

calling a function block from ST

calling a function block from ST

calling a function block from ST

calling a function block from ST

calling a function block from ST