Manual under construction...

Setup and Operation

A description of the Cloud Sensor Graph window, buttons and fields follows.

The Graphs

Most of the window is occupied by the graphs. The top graph charts the relative sky temperature, which is the indicator of cloudiness. The vertical scaling is fixed, and appears along the right side of the graph.

The second graph charts the ambient temperature. Again the axis labels are on the right, and they automatically re-scale based on the history of the temperature data.

The graphs are "real-time" in nature, which is to say that new data is added to them as time progresses. New data points appear on the right side of the graphs, and the historical data points scroll to the left to make room for the new data. This is similar in operation to a strip-chart recording device.

You will notice that the relative sky temperature graph changes color based on the sky condition. The legend for the graph color appears at the top of the graph. Two dotted lines appear on the graph to indicate the Clear/Cloudy and Cloudy/Very Cloudy thresholds as set in Clarity.

The horizontal axis labels appear in local date and time, and automatically re-scale and re-format depending on the history length of the graphs (see below).

When the Cloud Sensor Graph is first started, the graph style (colors, line types, etc.) is set to a default. This can be customized to your preference by right-clicking on the graph. This will bring up a menu with various customization options. You can also click on the gray area separating the two axes and slide it up or down, changing the relative proportion of the graph area that each axis occupies.

By invoking the Graph®Setup menu item, you can set the following items:

Chart Title: Enter the title that you would like to have appear at the top of the graph in this text field.

Chart History Length: This determines how long the graph will remember data. Suggested values are from 1 to 48 hours, although 12 hours seems to be a good value for learning the characteristics of a site and being able to spot data trends well. Note that longer history lengths result in less frequent updates to the graph.

GIF Chart Image Filename: Enter a filename here to save the chart output every time it updates. This is useful if you run a web server on your observatory computer, for example, and want to access the chart image from a remote location via the internet. The filename must end in ".gif".

Saved Image Size: Enter the pixel dimensions of the saved chart image here.

Chart Update Command: If you want a program to execute every time the chart updates, you can enter that command here. Example:

"c:\windows\system32\ftp.exe" -s:ftp_script.txt

Note the double quotes, which are recommended. The example above will cause the FTP script contained in the file "ftp_script.txt" to be run every time the chart updates. You can test the command by clicking the "Test" button next to it on the Graph Setup form. The FTP script must be located in the directory where the Cloud Sensor Graph is installed (e.g., C:\Program Files\RC-Astro\RC-Astro Cloud Sensor Graph).

Here is an example ftp script:

open ftp.example.com
username
password
cd directory
put chart_temp.gif
rename chart_temp.gif chart.gif
quit

You must supply the FTP host name, the username, password, and upload directory. The above example script assumes that the GIF Chart Image Filename is set to "chart_temp.gif". The rename command in the FTP script helps eliminate any collision between the FTP program trying to upload the file and any other access to the file (e.g., being served by a web server).

If the Chart Update Command hangs for whatever reason, you will find a minimized command window on the windows taskbar. You can open this to see what is going on with the script and debug any problems.

Very Cloudy/Wet Command: This is similar in operation to the Chart Update Command described above, but it only executes when the cloud sensor reports a Very Cloudy or Wet condition. This can be used to trigger a program that will close your observatory, for example.

Important: No warranty, express or implied, is made here regarding the efficacy of this function. No liability is assumed for any damage arising from a failure of this function. Please test this thoroughly before trusting it with your observatory and equipment. It is also highly recommended to have a hard-wired secondary system (i.e., one not relying on a PC) using the Cloud Sensor's relay output to trigger dome or roof closure in the event of inclement weather. Also, safe operation of this function requires that your observatory roof or dome can be closed with the telescope in any position to avoid telescope, mount, and/or observatory damage.

Two other items appear under the Graph menu:

Graph®Reset Style

If you should happen to change the graph style to something you don't like, you can click this button to reset it to the default style.

Graph®Clear Data

Use this button if you should need to clear the chart data, leaving a blank graph.