Hello,
If you are using any of the plugin’s versions that include the Date/Time module (the Developer and Platinum versions), and you want get the hours between two date fields where are enabled only the time sections, for example: fieldname1, and fieldname2, you should use an equation similar to the following one:
DATEDIFF(fieldname2, fieldname1, 'hh:ii', 'h')['hours']
If you want get the result with the format: hours:minutes, the equation would be:
(function(){
var result = DATEDIFF(fieldname2, fieldname1, 'hh:ii', 'h');
return result['hours']+':'+result['minutes'];
})()
If your version of the plugin does not includes the Date/Time module, you should convert the date/time fields in javascript Date objects, and implement the equation calling the Date object methods (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date). For example, if you want to convert the fieldname1 in a Date object, the piece of code would be:
var date_obj = new Date(fieldname1*86400000);
Best regards.