
Re: PI Processbook
Asle Frantzen Feb 20, 2014 9:53 AM (in response to Darren.Metcalfe)Hi Darren
A simple method I've used before would be to create a Performance Equation returning 0, 1 or 2 (or possibly 1, 0 or 1) according to the three outcomes of this. If it's a weekly number only to be compared to last weeks number, you can just use simple PE functionality to compare this week's number to PrevVal(...).
In ProcessBook you'd use a multi state functionality on three graphical symbols. I've found it best to use symbols without a black border, and then place the three so that they overlap. The multi state will have to be set up so that the color is transparent (none) when it's out of state, and a good color when the state matches your arrow. I used a green arrow pointing upwards for a positive number, a yellow arrow pointing straight forward for the 0 number (same as last week), and a red arrow pointing downwards for a negative number.
If you need a more advanced calculation on determining the slope of a trend, you'll be looking at calculating the derivative for the trend. I think there's a function in PE called Arma, but I haven't used it.

Re: PI Processbook
Marcos Vainer Loeff Feb 20, 2014 11:59 AM (in response to Asle Frantzen)Hello,
Arma actually calculates dynamic response for Auto Regressive Moving average model, which is very useful for process control engineers.
@Darren: I don’t see any function to calculate the derivative but you can apply its definition for discrete time series, and it will work great.

Re: PI Processbook
Darren.Metcalfe Feb 20, 2014 4:02 PM (in response to Asle Frantzen)Hi Asle
Thanks very much for your help, I'm looking into your method and using the knowledge. Could I just ask, did you use symbols from the symbol library or add your own symbol? The reason I ask is the the symbols within the symbol library all have black borders and if I add my own symbol, I'm unable to add a multi state function to it as the option is not available.
Many Thanks

Re: PI Processbook
Asle Frantzen Feb 21, 2014 8:59 AM (in response to Darren.Metcalfe)I had to look this one up, I see the date on the PDI file is 2009 so it's a bit long time ago :)
Under the symbol library ASHRAE Ducts, the first symbol is a simple, black arrow called 'Duct air flow direction'. Using this you'd be able to accomplish what you want.
(I see I've used the Arrange > Rotate command to rotate the upwards/downwards arrows indicating this week's value has changed)

Re: PI Processbook
Darren.Metcalfe Feb 24, 2014 3:14 PM (in response to Asle Frantzen)Thanks Asle for your assistance. I'm using your advice and have created a PDI similar to your original description. Many Thanks


