Step7 Basic operations, program blocks - DCE FEL ČVUT v Praze
Step7 Basic operations, program blocks - DCE FEL ČVUT v Praze
Step7 Basic operations, program blocks - DCE FEL ČVUT v Praze
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FB and FC parameters<br />
Simple types<br />
BYTE, WORD, BOOL, etc.<br />
Complex types<br />
ARRAY, TIMER, COUNTER, etc.<br />
BE CAREFUL: when calling <strong>blocks</strong> several times in one scan cycle<br />
Rising edge detection<br />
Timer value<br />
…<br />
• There is one or more data <strong>blocks</strong> (DB) dedicated to each<br />
function block (FB)<br />
– e.g. operation of more devices of the same type with different<br />
parameters<br />
• Multiple‐instance call<br />
– The called FB is a static parameter of the calling function block<br />
– The called FB are under Multiple Instances<br />
– The upper FB must be created with “Allow multiple instances”<br />
– Not so many DBs needed<br />
Multiple-instance<br />
FB<br />
(upper laying)<br />
in …<br />
out …<br />
stat motor1 FB1<br />
stat motor2 FB1<br />
FB10<br />
Function block calls<br />
FB1<br />
FB1<br />
FB1<br />
Function <strong>blocks</strong> in the<br />
static parameters of<br />
the upper FB<br />
3.10.2012<br />
8
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