Amusement Park Skyride Wind Speed Monitor

I need to make a program which used an ADC (I have to define a custom function in this particular PLC, a Trilogi MD model) that is connected to the output of an anemometer. The A/D is unipolar, 8 bits, and 10V FS. The max output numeric value will then be 255 decimal, obviously. we'll say that Wind speed would then be a range from 0 to 75 mph ( 0 Volts = 0 mph, 10 Volts = 75 mph) ...

I have inputs RUN which indicates the ride is running and CLEAR which is a maintained selector switch that turns off the Audible Alarm AALARM.

The ouputs are AALARM which is the audible alarm and is on continuously when energized until disabled by the CLEAR, and VALARM which is a red light on the control panel indicating unacceptable wind conditions. When energized it continuously flashes on 0.5 s off 0.5 s. CLEAR has no effect on it. It will stop flashing whenever the wind speed drops to an acceptable level.

I have this program about done, even though I have summarized the whole thing for sake of avoidance of confusion, but I am having serious issues with the custom ADC function. If anyone has experience with this and can drop me some hints I would much appreciate it.

This is a homework assignment so I do not desire a full solution. Just enough to get me headed in the right direction

Thanks a lot.

I have quite a lot of experience with the Triangle Research PLC's.

Just off the top of my head but I would think the custom function for the analog input should go something like this

A / 55 = ADC 1 ' This should scale the input from 0-75 ( 4092/75 is roughly 55, this plc does not handle floating point math) and store it in memory location A.

You can then use a (if, or, then) statement to enable your outputs as you please.

Example

A/55 = ADC 1

if A > 75
then
clrio output 1 (this clears output 1 regardless of state.)
endif

This is a very simple way of doing it, hopefully this helps.

I have tried that and I am having trouble with it still.
When the RUN input is off, the system in completely disabled. That is, both alarms are disabled, and the ADC is not sampled.
When RUN is on the system is operating. Initially both alarms are off. The system continuously samples the ADC input, mathematically scales it to mph and compares it to 25. If the wind speed is less than 25, nothing happens. However, if the wind speed is greater than or equal to 25 for more than 5 seconds, both AALARM and VALARM are activated. If, during the 5 second time period the wind speed falls below 25 mph, the timer is reset and no alarms occur. In short, it is ok for the wind speed to be above 25 mph as long as it doesn't remain there for more than 5 seconds.

Once an alarm occurs, AALARM is latched, that means that even if the wind speed falls to an acceptable value, AALARM will continue until it is reset by a CLEAR input.

I did the same sort of thing with a system.

I was monitoring the turbo boost pressure of a diesel engine, when it went above the setpoint for a specified time in seconds it would shut down 4 feed conveyors into a hammer hog.

If the boost pressure dropped below the setpoint before the allotted time the system was reset.

I am very busy right now, lots of 12 hour days, so I will try and show you exactly what I did within the next day or so.

You should also try out the Triangle Research forum, tech support will usually answer within a day or so.
http://www.tri-plc.com/yabbse/index.php

Willpower

b=adc(1)

z=75*b/255

if z>=30 then
setbit output[1],0
setbit output[2],0
else
clrbit output[1],0
endif

that is what I have - now I have a problem with my ladder logic because the program is not testing is the input >=30 it is just staying on all the time....

Here is what I have so far

Timer 3 N.O. ======================================== {CusFun1}


ADC1 N.O. ======================================== (CR1)

CR1 N.O. ========CLEAR N.C.====================== (AALARM)

the rest is just a flasher circuit that energizes when CR1 is on....CR1 is the output relay that is supposed to only come on when the ADC is greater than or equal to 30...it is staying on all the time!