adccommunitymod (AutomationDirect) asked a question.
Created Date: March 03,2010
Created By: PeakLifestyles
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I am relatively new to analogue temperature and humidity transmitters and am wondering about interpreting values. I setup a CLICK C0-02DD1-D and connected a Dwyer RHT-W Temperature and Humidity Transmitter (4 - 20mA). Everything works great and I am able to send out the data register values over a serial connection to a PC that I am using for data logging. The only problem has been trying to find an explanation of what the actual values mean. The humidity value seems to be an actual relative humidity value (%RH) because it is the exact value as another self contained measurement device I have. The temperature value however appears to be offset and this is where I would like to understand how I determine what math function to apply. The specs for the device indicate a temperature range/limit of -40°F to 140°F. Do I simply offset my output value from the PLC by 40 which would actually then match the value from my other measurement device. This all seems to make sense and is fairly straight forward but I don't understand why I am struggling to find any documentation to support my guessing.
Created Date: March 03,2010
Created by: Do-more PE
That sounds correct.
Created Date: March 06,2010
Created by: Dan @ CHP
Not sure if you 've already done this, but in the Click software go to the SETUP menu and click on CPU Built In I/O Setup. There you can choose the Input tab and set engineering units for your analog inputs. The destination registers will then contain meaningful data.
Created Date: March 11,2010
Created by: PeakLifestyles
Thanks for the hint. I didn't even think of that. This now saves me adding the math function in my code.
Created Date: March 03,2010
Created by: PeakLifestyles
I am relatively new to analogue temperature and humidity transmitters and am wondering about interpreting values. I setup a CLICK C0-02DD1-D and connected a Dwyer RHT-W Temperature and Humidity Transmitter (4 - 20mA). Everything works great and I am able to send out the data register values over a serial connection to a PC that I am using for data logging. The only problem has been trying to find an explanation of what the actual values mean. The humidity value seems to be an actual relative humidity value (%RH) because it is the exact value as another self contained measurement device I have. The temperature value however appears to be offset and this is where I would like to understand how I determine what math function to apply. The specs for the device indicate a temperature range/limit of -40°F to 140°F. Do I simply offset my output value from the PLC by 40 which would actually then match the value from my other measurement device. This all seems to make sense and is fairly straight forward but I don't understand why I am struggling to find any documentation to support my guessing.