4/16/2011 10:21 PM | |
Joined: 9/6/2008 Last visit: 3/29/2024 Posts: 134 Rating:
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i am not sure if is what you look for but perhaps it will help you to solve your problem or it will give you an idea how to make it. http://www.automation.siemens.com/mcms/programmable-logic-controller/en/logic-module-logo/application-examples/Pages/Default.aspx download the zip " storing analog min-max values" best luck |
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4/22/2011 1:15 PM | |
Joined: 8/16/2010 Last visit: 7/8/2024 Posts: 50 Rating:
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Hi HRPT, Firstly, I'm no expert and so this could be completely the wrong way of acheiving what you want to do,BUT, it does work (and believe me it took some head scratching)! As I see it, there are only a few instructions that have the retentive option, these being mostly timers, the up/down counter and hour counter and the only analogue function with retentive option is the analogue watchdog. Since we are working with analogue values I first tried using the watchdog but could not get my head round how to make this work in a way that would allow us to retain the last stored analogue value. Therefore I've opted to use the up/down counter. Basically I've used the counter to follow the analogue value. On start-up the retained counter value is fed through the analogue multiplexer to restore the value that was present before power was lost. There is one draw back though! The counter takes several seconds to reach the desired value if changing the analogue value by a siginifacant amount. However I'm pressuming that this isn't going to be a problem as in most circumstances analogue values normally change by small amounts in which case the counter will keep up quite nicely. I don't know if you preferLAD or FBD but hopefully you can follow what I have done. Regards, RandomCoder AttachmentRetentive Analogue Store.zip (1247 Downloads) |
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4/26/2011 4:51 PM | |
Joined: 1/5/2007 Last visit: 4/7/2023 Posts: 1690 Rating:
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Hi all, in the german part i have tell about analog value memories... "Hinweise zur Speicherung von (Analog-)Werten" Attachmentrefreshing_the_analog_output_every_5_seconds.zip (1117 Downloads) |
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5/3/2011 3:12 PM | |
Posts: 3 Rating:
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Hi Betel and All others, My first attempt to create the circuit that I needed, even before I made any postings,I used the PI-controller from the examples "Hinweise zur Speicherung von (Analog-)Werten" it is a good guidance, however I did not sucseeded.....because whenthe power from the logo! is off and on again,by the first refresh of the PI-controller you gonna losethe retentive valuesandonly the present values of that moment are available. So I have to figure it out how to countmy present (every 10 seconds) values by the values earlier counted (retentive), even in a situation when the power was down for some reason.....In the attachement is my solution, there are no commentsof the used blocks (yet), justrun it and move both analoge sliders to a position. HRPT AttachmentAnalogeValueCounter.zip (1171 Downloads) |
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