Holding temperature for a set time

[fios]

Hi all,

Bit of a brainteaser here maybe!

Attached is a section of a vi  have, where by when a set temperature is reached, the set time starts, then knocks the heater off.

When I run it on my PC, with no compact fieldpoint modules attached, (temperature shows 0 degs C) the timer kicks in no troubles.

However, when I connect up to the modules, all works well untill the temperature is reached (the wee light comes on too, saying it has reached the temp) but the timer never starts!

Any idea how or why this could be hapenning?  I'm using vers. 7.1.1 at the moment.

Cheers,

Steven

[TCPlomp]

Sorry Fios,

but your code is to messy to read properly. Take 10 minutes to do the following:
Left to rigth dataflow.
Smaller

Ton

[fios]

Tidied up now 🙂

Hope it helps 🙂

[YatinM]

Hi Steven

The reason why your timer doesnt start when your FP thermocouple passes the set temperature is because you put a 'equal to' function instead of a 'greater than or equal to' function. The way you have done it, results in the timer only starting when the temperature is EXACTLY the same as the set temperature, so if it jumps that then the timer will not start.

Regarding the tidying up, your VI is still quite messy. Alot of your case structures can be replaced by simple boolean logic, such as the 'Select' function, which can be found in the 'Comparision' palette on the Functions palette. You need to take some time and try to replace your case structures bacause all you are doing is either passing a true or default false state through them.

Hope this helps

YatinM

National Instruments UK

[fios]

Ah!  I'll try some things out then mate!

So without the TC module connected the '=' part of the logic wouldn't matter, but when the TC units are connected, because the '=' logic is there, nothing happens eh?

What woulkd I replace it with? Would a simple replacement to '>' suffice?

Cheers again!

[YatinM]

Hi

Yeh just replace it with a 'greater than or equal to' function (=>), should do the trick to start your timer. To test you could delete the FP express.vi and replace it with a dial control from the Numeric palette on your front panel. Then you can control the temperature output result by turning the dial.

Best Wishes

YatinM

NIUK