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Old January 9th, 2019, 04:45 PM   #1
mike3475
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monitor rslogix 5000 a tag

Hi,Guys:
we want to monitor a tag (PF525 drive output current) when drive output current is over the threat point at what exact time, we can use trend, the problem is we don't know when it happens, it could be once a week or twice a week, it very hard to trace it. we may use HMI to set up a alarm, but we didn't find a trigger point yet.
anybody has a idea?
thanks!
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Old January 9th, 2019, 05:06 PM   #2
scott.lawrence
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you could write trap logic to let you know when & to what value the current exceeds the alarm/setpoint
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Old January 9th, 2019, 05:48 PM   #3
beethoven_ii
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Assuming you're using Logix5000 you could set up a Message instruction to do a parameter read and read parameter 3 from the drive. Divide the value you get back from the drive by 100 and that will give the actual current of the drive in amps. Compare this to your limit and use the comparison to trigger an alarm if it ever goes above your limit then you'll have a log of when it happens. You could also compare the actual current value to another tag for the peak value so you'll know what the highest value the current has been.
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Old January 9th, 2019, 05:48 PM   #4
mike3475
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we want to know when the drive output current is over our set point.
for example: the drive output current is over 6A (set point) at 6:39 PM 1/9/2019, in fact we want to know another tag activity after this moment.If we don't use HMI.
Thanks!

Last edited by mike3475; January 9th, 2019 at 05:53 PM.
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Old January 9th, 2019, 06:17 PM   #5
dmroeder
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You can use a GSV instruction to get the PLC's time, when you get your over current condition, save a copy of the current time.

http://www.plctalk.net/qanda/showthread.php?t=75629
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Old January 9th, 2019, 07:20 PM   #6
mike3475
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got you.
thanks everyone!
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Old January 9th, 2019, 09:06 PM   #7
mike3475
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http://bryceautomation.com/index.php...wallclocktime/
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Old January 10th, 2019, 07:59 PM   #8
ArtWalls
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We implemented a poor man’s version of value trapping using the built-in digital alarms logged to an SQL server. The almd instructions allow for extra tags, we point them to the relevant tags in the PLC. After the fact, we look at the alarms in SQL and can tell exactly what tripped them, and when.
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Old January 12th, 2019, 12:33 PM   #9
mike3475
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Thanks!
I never use ALMD instruction before, anybody has any example for ALMD instruction?

Thanks!
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Old January 12th, 2019, 04:48 PM   #10
janner_10
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Keep it simple .. When your current > Your set point, use the RE to write the date time to an alarm time.
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Old January 12th, 2019, 07:04 PM   #11
ArtWalls
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We put an almd instruction on a rung and set up the conditions ahead of it. Create the alarm tag, then use 0,0,0,1 as the parameters. Open the alarm definition, put in a descriptive message. Then, add any related tags. In your case I would put the drive current, the setpoint if it changes, and the other tag you were concerned with. When the rung goes true, the alarm will trigger. If you are going to an SQL server, a timestamp will automatically be captured.
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