Generate the Chart Image
The third and last step is to generate the chart image. This page explains how to generate charts on a timed basis, as well as how to generate them on demand.
If a chart schedule entry has a timed frequency setting, then the Chart Scheduler must be run to generate the chart images on a timed basis. To do this, start the Chart Scheduler program. This is usually done by running a program called "*gencharts" as a background task. This program is not interactive; however, if you run it in a live PxPlus window, it will display polling intervals and the name of any charts currently being generated. (You can break out of the program by pressing the F4 or ESC keys.)
If more than one chart is scheduled for generation at the same time, they are generated sequentially. If a particular chart requires heavy processing, this may delay the processing of subsequent charts scheduled at the same time. If a chart consistently fails to generate, it is automatically removed from the schedule file after 90 days.
The appearance of the chart is dependent on the chart brand setting (see Define the Contents of the Chart). In a NOMADS environment, this is dependent on the setting of %Nomad_Chart$. Chart image generation supports Google and RGraph charts. The %Nomad_Chart$ setting can be set, for instance, in the START_UP program.
If you are running your application on a Windows server, the Chart Scheduler can be set to run as a Windows Service. A utility program called "*plus/winutl/chartservice" can be run to create a service called PxPlusCharts. See Installing Chart Generator as a Windows Service.
Chart images with the frequency set to On Demand can be generated from Chart Image Generation Schedule Maintenance or generated programmatically.
To generate a chart on demand using Chart Image Generation Schedule Maintenance, click to highlight the desired entry from the list of schedule entries and select the Generate button. If the selected entry is based on a Query+ AutoChart definition, the result is displayed, along with an option of deleting the generated image. If the entry is based on a user program, then the program will be called.
To generate a chart on demand programmatically, call the "*gencharts;Generate_Chart" program, passing the schedule item name as an argument, as in the example below.