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Redg PLC Scan Rate

Created by: onir at: 9/17/2013 12:18 PM (2 Replies)

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9/17/2013 12:18 PM	Rate (0)
onir Posts: 3 Rating: (0)	Dear Sirs, I have a small confusion: 1) is conversion time of analog input module = scan time? 2) if conversion time = 3ms and the analog module is configured as a remote IO module communcating with the main coontroller over ProfiNet then can we say PLC data update rate = 3 ms. Regards, Onir
onir Posts: 3 Rating: (0)
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9/17/2013 5:00 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 8/8/2023 Posts: 6818 Rating: (1349)	onir Dear Sirs, I have a small confusion: 1) is conversion time of analog input module = scan time? 2) if conversion time = 3ms and the analog module is configured as a remote IO module communcating with the main coontroller over ProfiNet then can we say PLC data update rate = 3 ms. Regards, Onir Hello, Just to share a point regarding "Scan Time" of PLC,This is a term required for the CPU to manipulate process image then execute OB1 and handle all interrupts.This time varies with type of CPU ,program execution load,communication and interrupts(rates).It is possible to know what is the latest scan time of CPU in H.W Config and max and min values in your case.For an S7-400 with fair load of program execution load and interrupts, this value would be around 60ms. Please, note update rate of 3ms in analog input module doesn't necessarily mean that this value is effective in program execution.There are some ways to update the process image or using hardware interrupts to have fast reaction to changes in process. Hope these comments help Hamid Hosseini
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9/18/2013 5:42 AM	Rate (0)
onir Posts: 3 Rating: (0)	Dear Sir, Thanks a lot for this explanation. Regards, Chetna Gupta
onir Posts: 3 Rating: (0)
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This contribution was helpful to 1 thankful Users hdhosseini

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