Timer

[opticaldynamics]

Hey I am working with a reactor that is set to heat up to 146C then cool down to 80C and stay at 80 for 25 hours. How would I write a code that would start counting down the 25 hours when the reactor gets to 80C so we are able to see how much time is left?

Thanks

[AzeoTech]

Just set a global variable to systime() when the cool down starts, and then display 25 * 3600 - (systime() minus that variable) for the amount of time left (in secs). OK:

global starttime = systime() // when the 25 hours starts

the expression for elapsed time (in secs):

(systime() - starttime)

in hours:

(systime() - starttime) / 3600

for remaining time (in hours from 25)

25 - (systime() - starttime) / 3600

[opticaldynamics]

Okay, so how would i incorporate that into my code so it will start as soon as the temperature is 80? my Code looks like this..

using("device.labjack.")
include("c:\program files\labjack\drivers\labjackud.h")//Both lines of code establish connection with LJ

//Declare global variables that will be used throughout sequence
global uppertemp
global setpoint
global synthesistime
global hysteresis
global systime()

//ZnO Synthesis, heat up to a certain temperature (uppertemp)
while(min(controltemp[0,4])<uppertemp)
   ePut(0, LJ_ioPUT_DIGITAL_BIT,6,0,0)//set FI06 to output-low (heater on)
   output=3.6
   delay(1)
endwhile

//Cool to set temp
while(max(internal[0,4])>setpoint)
   eGet(0, LJ_ioGET_DIGITAL_BIT,6,@FI06Reading,0)//set FI06 to input (heater off)
   output=0
   delay(1)
endwhile

//Control for synthesis time
private starttime = systime()
while(systime()<starttime + 3600*synthesistime)//control for 1 hour X synthesis time
   if (internal[0]<setpoint - hysteresis)
	  ePut(0, LJ_ioPUT_DIGITAL_BIT,6,0,0)//heater on
	  output=3.6
   endif
   if (internal[0]>setpoint-1)
	  eGet(0, LJ_ioGET_DIGITAL_BIT,6,@FI06Reading,0)//heater off
	  output=0
   endif
   delay(5)
endwhile


eGet(0, LJ_ioGET_DIGITAL_BIT,6,@FI06Reading,0)//heater off
output=0

Thanks

[AzeoTech]

Just make your "starttime" variable global instead of private so you can access it from screen components, and replace the 25 with synthesistime in my expressions. Also this line:

global systime()

is invalid. Systime is a reserved function so can't be used as a variable, nor needs to be declared, and putting () in a variable declaration is not valid either. The sequence executor probably just skips over the line.

[opticaldynamics]

okay, I have the timer working in a way. the code seems to work and it displays a number of hours left and decreases over time but it comes up as a huge number such as 125786129.688 hours left..

[AzeoTech]

Everything in DF is in seconds. Perhaps you forgot to divide by 3600? Of course that's still about 35,000 hours, so there is something else wrong in your math. I'd need to see your script to help any further.

[opticaldynamics]

Under Variable Value Component, we have the caption called remaining time. the expression for it is:

Starttime- (systime() - starttime) / 3600. should the First starttime actually say synthesis time since our synthesis time is set to 25 hours?

thanks

[AzeoTech]

Correct, provided sythesis time is in hours, not seconds. If its in seconds, it will need to be SynthesisTime / 3600, or do the appropriate algebra to simplify it.

[opticaldynamics]

ok thanks for all your help I think I have it working now