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| 2/15/2011 1:34 AM | |
Joined: 10/7/2005 Last visit: 1/20/2026 Posts: 3054 Rating:
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Hello fvanluchene please try the following: FC105: IN PIW 272 // Raw AI, range: 0-27648 (=4-20mA = 0.0°-100.0°C in your case) HI_LIM 100.0 //Scaled HI limit as REAL, note decimal point ! LO_LIM 0.0 //Scaled LOW limit as REAL, note decimal point ! BIPOLAIR FALSE RET_VAL MW2 OUT MD100 // scaled AI as REAL FC106: IN MD100 //scaled AI as REAL HI_LIM 100.0 // REAL value, note decimal point ! LO_LIM 0.0 // REAL value, note decimal point! BIPOLAIR FALSE RET_VAL MW4 OUT PQW 282 Having said the above, in your particular test case of: AI: 0°C=4mA => AQ: =0V output AI:100° C=20mA => AQ: =10V output. you can simply do: L PIW 272 // Raw AI (range: 0-27648 => 0°C=4mA; 100°C=20mA) T PQW 282// =AQ (range: 0-27648 => 0V-10V) I hope this helps and remember that you canuse <F1> on FC105 and 106 to get the context sensitive help for these Blocks. |
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| 2/15/2011 7:15 PM | |
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Posts: 19 Rating:
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It helps me alot but there are still some strange things to me. in fc105 i took the wrong input because i was a bit to fast. but the hi_lim from fc105 and fc106 is strange could you explain why you take 100 is the hi_lim maby in %? because if you think logic the FC105 hi_lim should be 100 like you said because you have 100°c and the hi_lim of fc106 should be 10 because you have max 10V. and your other solution looks verry easy maby to easy to work but i will try it. but it will probably give some problems when i use fc41 or another block of the pid-regulator. sorry for my bad english |
| 2/17/2011 1:18 AM | |
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Joined: 10/7/2005 Last visit: 1/20/2026 Posts: 3054 Rating:
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Hello fvanluchene I took 0.0 & 100.0 as FC105's Low and Hi limits because you said that these equate to the 4-20mA as measured by the temperature probe. These are simply the Engineering Units Low and Hi limits that correspond to the capabilities of your AI sensor. FC106 now has the same to ensure that the 0.0-100.0 REAL value is "unscaled" to 0-27648 INT value, which is then converted by the AQ card to 0-10V. As said before, pelase have a look at FC105's and FC106's help (click on each and hit F1), you'll also find some really good info on analogue signal representation in chapter5 of the SIMATIC S7-300 S7-300 Module data manualand plenty of Forum related entries concenring this. I hope this helps |
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