I'd like to use a tag to create an Upper Control Limit (UCL) and a Lower Control Limit (LCL). This involves calculating the mean and standard deviation for a period of time. The formulas would be:
What would be the best approach to do this? I was looking at doing an I/O Calc tag, but the avg() and SDev() functions are not availalbe. I also tried looking at the Historical Statistics tag but all I can do is calculate the average over a period of time, but not the standard deviation. Any insights would be helpful, thanks!