FX3G-2AD-BD Store Peak Value

3 posts in this topic

Good day,

I'm new to this forum and to mitsubishi PLC but was hoping for some assistance with a programming issue.

I have been through the hardware and programming manuals without luck for this issue.





Structured ladder/FBD

Current input mode on: M8260 (first board, first input)


What I need to do is to record the peak value over a cylinder stroke period. The hardware manual explains how to average the value using averaging time, however I basically need to peak hold and send that to a D register for go no-go compare. 


Process as follows:

Contact closed, monitor D8260, contact open, move peak value from D8260 during monitor duration to D205. 


Thanks in advance for any assistance.



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You could do it very simply with  commands  such as:

IF D8620 > D205 THEN MOVE D8260 to D205

IF D8260 <= D205 THEN MOVE D205 to D205.

You would just code this logic in ladder format and also determine when you wanted to reset D205 (MOVE 0 to D205)

How successfull it would be would depened on the speed of the cylinder stroke compared to the scan time of the PLC.

Say the piston took  1 second to cycle and the scan time was 5 ms, then the comparison would be done 200 times during the stroke of the piston, so the resolution of the maximum value attained would be quite good, but whether or not it's actually good enough depends on what you are trying to do with it.

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Just the answer I was looking for, thank you very much!


Apologies for the late reply, work firewall blocks my access to sign in here. 

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