I need to log data onto a PLC that is not normally connected to a network or HMI terminal. I need periodic (every 15 minutes) storage of 3 analog values and one digital value. I only need the last 24 hours of data so I'm planning to build a queue that will overwrite the oldest data so I don't run out of space. I have written programs to store the data directly into the PLC memory in the past but I don't want to hard code every register. I know Siemens has a way to use pointers to programatically change registers but I have never used them. I don't know what Rockwell offers. Does anyone have suggestions or example code? I can use either a Siemens S7-300 or a ControlLogix. Which will be easier for this type of program? (I have done some basic programming on both)
Thanks for the tips
Thanks for the tips