Control Logix Controller Scan time

ss4884

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Join Date
Mar 2009
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Dear Friends,
we all know that we can get the Scan time of a Task using GSV Instruction. I would like to know is there any Method/formula to get the Scan time of the Controller.

Can any one tell me the relationship between Controller I/O-Memory & Scan time, How I/O memory is affecting the scan time of Controller?
 
CLX scan time

Hi,

In CLX you can monitor scan time for everything thru tool "task monitor". Install this tool and you can monitor performance of routines, programms, tasks , memory and CPU as well.
 
Thanks CLXenggr,
I want to monior the Controller scan time programmatically not via task monitoring tool, Do u any idea to accomplish the same, if have please let me know..
 
CLX ScanTime

As CLX is NOT a PLC, (it is PAC) the normal concept of scantime does not apply to it. Controller executes (scans) Tasks/programms and IO asynchronously hence like PLC you do not have scan, like Input scan, programm and output scan.
IO's are accessed as per RPI times or module's settings.
 
If you are looking for instantaneous scan time you can use a GSV in the continuous task to read the WALLCLOCK value (DINT[2] array) and take the delta of the LSW of the array between scans. This is a measure in microseconds of how long it took the processor to make one complete pass and get back to the continuous task. Keep in mind that this value can be extremely variable if you have multiple periodic tasks scheduled and/or alot of I/O. But I have found this to be the most accurate indicator of composite scan time available internal to the plc.

Keith
 

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