Michael McSharry
Active Member
The limits are associated with each WebControl input. If you want both a control function and an alarm function then you will need to use two inputsAre lower & higger limits the thresholds associated with each measure in the Webcontrol board?
In my mind I wanted to keep these thresholds for trigger a low or high alarm and control the HVAC with a soft setpoint ( I mean a value stored in board memory, this value that I can change from web browser)
To achieve this it means a computer must be running xapmcsWebControl, because the WebControl board isn't able to do that. Correct?
In my project the board must be able to run alone.
The board is able to perform proportional control without a PC connected. This should be good engough for most applications. At some remote location you can use xapmcsWebControl to adjust a setpoint and it will download the apprropriate parameters to the WebControl module to control to this new setpoint. xapmcsWebControl would only need to run when you want to change the setpoint.
One issue also is that you said here above about temperature accuracy. If 1-wire temperature measurement is not very accurate that's a problem. May be this can be solve by using another tempertaure sensor (such as PT100) on an analog input.
The temperatrue sensor supported by WebControl is plenty accurate for proportional control. You need a DS18B20 made by Maxim-ic and with a stable voltage source. That is a shortcomming of the WebControl module is its robustness for ranges of DS18B20 sensors that are available. You may need a more accurate sensor if using PD control as the derivative calculation will be affected by it. In your case it does not matter since you will want the control to be dependent only on the temperature error and not the rate of change of the error.