Cumulative flow

[justwhy2003]

Hi If im using a Mitsubishi FX3u with FX2n-8AD analogue input card to measure the reading from a flow meter on a 4-20mA (prob 0-4000 res) loop and displaying it on Citect SCADA, what are the options for recording and displaying cumulative flow? It it ok just to sample the flow at say 5 second intervals and add this value to a battery backed up register in the PLC or will this increase dramatically very quickly and fill the register. Or should i look to the SCADA to provide this feature? If i could id preffer to do it in the PLC as id trust the PLC memory more than the SCADA. Although i also have to configure the SCADA to produce weekly reports which may help me out in this area. Any thoughts?

[gromit]

I'm not familiar with the Mitsubishi FX3u but I could answer this question in pretty broad terms. If the flow is measured in GPM and you are wanting to save the totalized/accumulated value every 5 seconds, then you need to divide the realtime flow value by 12 and then add it to the total to account for the rate in minutes.