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Lead-lag filter

10/26/2010 6:43 AM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 1/5/2026 Posts: 6892 Rating: (1368)	Hi I am looking for an algorith which can be used to implement Lead-Lag filter in SCL.Is there any function in siemens's library which functions like this filter? See the attachment for a similar function which is available in PID modular control. transfer function=(1+t1s)/(1+t2s) Best regards Attachment diff.zip (659 Downloads)
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10/26/2010 2:45 PM	Rate (1)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 1/8/2026 Posts: 1561 Rating: (540)	Try the following. It might not do what you need exactly, but it is a good starting point. [code]FUNCTION_BLOCK FB1000 TITLE = 'Lead Lag' NAME : LEADLAG VERSION : '1.0' VAR_INPUT IN {S7_dynamic := 'true'} : REAL; LEAD_T : REAL; LAG_T : REAL; INIT : BOOL; INIT_VAL : REAL; SAMPLE_T {S7_link := 'false'; S7_sampletime := 'true'; S7_visible := 'false'} : REAL; END_VAR VAR_OUTPUT OUT {S7_dynamic := 'true'} : REAL := 0.0; END_VAR VAR SaveVal : REAL := 0.0; END_VAR VAR_TEMP Diff : REAL; Lead : REAL; Lag : REAL; END_VAR BEGIN IF INIT THEN; SaveVal := INIT_VAL; END_IF ; Diff := IN - SaveVal; Lead := (2.0 * LEAD_T + SAMPLE_T) / (2.0 * LAG_T + SAMPLE_T); Lag := (2.0 * LAG_T - SAMPLE_T) / (2.0 * LAG_T + SAMPLE_T); OUT := Lead * Diff + SaveVal; SaveVal := IN - Lag * (IN - SaveVal); END_FUNCTION_BLOCK[/code]
	Last edited by: smiffy at: 10/26/2010 2:52 PM Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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10/26/2010 3:38 PM	Rate (1)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 1/12/2026 Posts: 12480 Rating: (2722)	Hello hdhosseini; Have a look at the attached document, it describes FC80 from the TI-S7 library: lead-lag algorithm. Hope this helps, Daniel Chartier Attachment TiS7_FC80.jpg (1562 Downloads)

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This contribution was helpful to 1 thankful Users hdhosseini