9/23/2009 11:50 AM | |
Posts: 11 Rating: (1) |
Hi, I've found that the secret to getting accurate flow total integration from a flow rate input is to carry out integration addition using the raw 6400 - 32000 input via an interrupt controlled routine (I'vehad accurate results using 10ms interrupt). Attachedare example subroutines for such an application. First subroutine is called on first scan to initialise the interrupt routine. The second is the interrupt subroutinewhere two totals are calculated. One is a overall flow total volume since system started, the other is a volume used to trigger a regeneration sequence after which it is reset to zero. There is also facility to overwrite the calculated overall flow total volume from attached HMI screen if the software calulated value gets out of sync with the flow instrument calulated total which can happen over extended periods of operation and also if the PLC has to be stopped. Hopefully the networkcomments make the logic clear but please feel free to ask questions. regards, Corby AttachmentS7-200 flow totalise.pdf (738 Downloads) |
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