... and if you'll post your .RSS file, we'll be happy to take a quick look at it and see if we can help identify any specific "gotcha" issues ...
link on "how to post a file" just in case you need it
can you tell us exactly what type input module you're using? ... and what will be a typical range of values (in degrees F) for your application? ... it's a pretty safe assumption that -327 to 760 is probably not the normal range of values your system will be dealing with ...
point: we MIGHT be able to recommend some mathematical tricks to improve your system's resolution and response if you can give us more details about your application ... hint: suppose that your process normally operates in the range of 70 to 500 degrees F (example: from room temperature to something suitable for an oven) ... if you just “plug-and-play” with the thermocouple’s full –327 to 760 degree input range and simply convert it to the customary 0 to 16383 range for the PID, look at what happens ... at the lowest input value of 70 degrees, the PID will see an input of 5983 ... at the highest input value of 500 degrees, the PID will see an input of 12464 ... 12464 minus 5983 equals 6481 ... 6481 divided by 16383 equals 0.395 and change ... basically then, all of your PID’s response will be limited to only about 40% of its “full scale” range ... specifically, the PID will never “see” an input either above or below a 40% band of its available range ... more specifically, about 60% of the PID’s available range is “wasted” and unavailable for control purposes ... now in many application this won’t amount to anything serious ... but in SOME applications this will give “clunky” control ... so one specific question would be: does your input module support a “scale for PID” setting? ... if it does, then you might want to consider letting the module provide a “raw” input value which ranges from 0 to 16383 at I:4.0 ... and then rescaling the data for the operator’s interface to accommodate that new range of values ... major concept: the address I:4.0 is an integer ... it can represent the value “98” (as in degrees F) ... but it cannot represent “98.6” (as in normal body temperature) ... so in most cases, the “raw” range of 0 to 16383 (assuming that it’s available with your module) usually gives better control than a “scaled-to-degrees-right-out-of-the-module” value ... and for completeness, note that some modules provide an “engineering units X 10” scaling feature ... does yours? ...
of course all of this is pure speculation at this point ... we don’t have enough detailed information about your particular application to give you any specific advice ... but the more detail you can give us, the more detailed the advice will be ...
and finally ... a little personal background information might help us to help you better ...
so ... are you already familiar with PID in general? ... is this your first "SLC" PID experience? ... are there any pre-existing PID loops in this same program? ... do you already know how to "tune" the loop? ... are there any safety concerns that we need to consider? ... do you already know how to handle an operator’s input for things such as “manual” to “automatic” control? ... what is your deadline on this project? ... please note that "As Soon As Possible" is not a valid answer ...
