Meta Point Help

[Pikey4]

Hi,

Trying to monitor cyclic fatigue on a small project, and can manually do it in excel but it's messy and ideally would like it data logged.

I though the easiest way would be a meta point such as:

if (p445.lastValue(101) > (p445.lastValue(102), (p445.lastValue(100))));

// means the value has hit peak ??
{
	return 1;
}

if (p445.lastValue(101) > (p445.lastValue(102), and < (p445.lastValue(100))));

// means the value is still climbing ??
{
    return 2;
}

if (p445.lastValue(101) < (p445.lastValue(102), (p445.lastValue(100))));

// means the value has hit trough ??
{
	return 3;
}

if (p445.lastValue(101) < (p445.lastValue(102), and > (p445.lastValue(100))));

// means the value is still falling ??
{
    return 4;
}

However this only returns a "1" no matter what, so I obviously have done something wrong.

I was using "lastValue(101)", "lastValue(100)" & "lastValue(102)" only because the point is Persistent TCP (with Live updating) and I didn't want to be looking at the un-updated value. (if that makes sense). So perhaps this is part of the problem??

Or I have gone completely the wrong way around this and I need to be looking at an alternative solution.

Any assistance is as always greatly appreciated,

A picture paints 1000 words:

Cheers!

[CraigWeb]

Hi @Pikey4

I believe your first if statement is short-circuiting. Your logical operators are not correct.
eg:
if (p445.lastValue(101) > (p445.lastValue(102), (p445.lastValue(100))));
should be
if (p445.lastValue(101) > (p445.lastValue(102) && p445.lastValue(101)>(p445.lastValue(100));

Might help to read through this site.
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Logical_Operators

[phildunlap]

@pikey4 said in Meta Point Help:

I was using "lastValue(101)", "lastValue(100)" & "lastValue(102)" only because the point is Persistent TCP (with Live updating) and I didn't want to be looking at the un-updated value. (if that makes sense). So perhaps this is part of the problem??

I didn't understand that. Using lastValue(100) will give you the hundredth value ago. That seems strange to do, and I'm not sure what this explanation is saying. I think I may go about doing something like this by having the meta point activate on a cron and check to see if the point has been updated / sync'ed and it can loop over the values in the next time period, based off the time of the source point and the last time of the meta point.

[Jared Wiltshire]

@Pikey4 as @CraigWeb said you have incorrect expressions inside your if statements. Try this -

var targetIndex = 100;
var prevVal = p445.lastValue(targetIndex - 1);
var thisVal = p445.lastValue(targetIndex);
var nextVal = p445.lastValue(targetIndex + 1);

if (thisVal > prevVal) {
    if (thisVal > nextVal) {
        // peak
        return 1;
    } else {
        // still climbing
        return 2;
    }
} else {
    if (thisVal < nextVal) {
        // trough
        return 3;
    } else {
        // still falling
        return 4;
    }
}

or a slight variation which you may prefer

var targetIndex = 100;
var prevVal = p445.lastValue(targetIndex - 1);
var thisVal = p445.lastValue(targetIndex);
var nextVal = p445.lastValue(targetIndex + 1);

if (thisVal >= prevVal && thisVal >= nextVal) {
    // peak
    return 1;
} else if (thisVal >= prevVal && thisVal < nextVal) {
    // still climbing
    return 2;
} else if (thisVal < prevVal && thisVal < nextVal) {
    // trough
    return 3;
} else {
    // still falling
    return 4;
}

[Pikey4]

Thanks for helping out @CraigWeb @phildunlap @Jared-Wiltshire ,

I couldn't get it to work with a Persistent TCP data on central server, so set up on an ES on Site and it seems to be tracking good. All the 4's and 1's are lining up where I expect them.

Thanks Again.

I got this to work:

var prevVal = p709.lastValue(2);
var thisVal = p709.lastValue(1);
var nextVal = p709.lastValue();

if (thisVal >= prevVal && thisVal >= nextVal) {
    // peak
    return 4;
} else if (thisVal >= prevVal && thisVal < nextVal) {
    // still climbing
    return 3;
} else if (thisVal < prevVal && thisVal < nextVal) {
    // trough
    return 1;
} else {
    // falling
    return 2;
}