temperature change from 1 state to another

[yongster]

hi
i have a vi using state machine

generally, this vi is used to heat a device to 3 different temp for a reaction

but i have a problem

the original states were like this

Init--> Init heat (heat to 90 deg c) --> Init Denature ( maintain 90 deg c for 30 s) --> Denature( maintain 90 deg C for 30s) --> Cool to anneal( Cool to 55 deg c) --> anneal(maintain at 55 deg c) --> heat to ext(heat to 72 deg c) --> ext (maintain at 72 deg for 30 s) thereafter return to denature and continue for 20 cycles

but later i combine init heat + init denature into 1 state, cool to annel and anneal to 1 state and heat to ext and ext to one state

the reason is because when init heat state change to init denature, instead of maintaining the temp at 90 deg C, it dropped during transition

but when i combined the above, there is a problem in the setting of the time,..............for e.g. as attached,  in the state init  denature, i have 2 timings -- init heat and init denature timing, by rite when the condition is reach, the init denature timing will start from 0 for a predetermine
time however in my case, instead of init denature timing starting from 0, it continue  from the init heat timing thus it will be inaccurate when running the predeterme timing......

any one knows how to overcome this??

any help is greatly appreciated

[Tom Haggerty]

What do you mean "it dropped during transition."  If you are maintaining temperature at some level, then the transition should have no affect on the temperature unless you reinitialize or have wired a default number to the temperature you are trying to control.  I tried loading your program.  I don't have the instrument controls for the instrument you are using -- not a problem -- but it is hard to follow what you are doing.  It looks like you have many different setpoints all coming from the ni435x read.vi in a 2d array.  You should check that the values you expect out of that array are correct for each of the points that you use it.

Tom

[Tom Haggerty]

I read your question again... Sorry the first response is not what you were looking for.  I looked at the code where you switch cases after the temperature is in range.  The only thing you do there is switch which indicator the elapsed time  goes to.  You need to reset the time if you want the denature indicator to start from zero seconds. 

Tom

[yongster]

Hi Tom
thks for the reply

just to explain a bit more on the "drop during transition"by an example

say i have 2 case
Case A: purpose to heat device to 90 deg C
Case B: purpose to maintain 90 Deg C

by rite, during the transition from A to B, the temperature shall fluctuate around 90 deg C
but what i observed is different from what we expected, when A change to B, the temperature will drop from 90 to around 70 ++ before raising tp 90 deg c when case B is running

i not sure does this have any impact, i did initialise these temp at the first state " init", will this cause the above??

[Tom Haggerty]

You could do this by subtracting the init heat time from the elapsed time in the False case and wire that to init denature.  But you would also need to wire that result out of your case to the Greater than or equal compare used to tell when denature time is up.   I won't be critical with you but there are many ways you could improve your code!

Tom

[yongster]

yap i understand your point......
there are certainly improvement needed for my code.....

[yongster]

yap i understand your point......
there are certainly improvement needed for my code.....

[Tom Haggerty]

As for the drop in temperature, depending how quickly it drops it may just be the transition taking a long time because there are so many things to set up in each case.  BTW, you are not running the program with execution highlighting, correct?  If you did that would cause a large delay in state transition.

Tom

[yongster]

nope, just running it as per normal
in any case, i will tried out what u suggest

thks..........