I see.
I'll document it here just so others can understand and maybe help.
The value for a date/time TV is stored in a hidden input field as such (in my case tv24):
<input id="tv24" class="datefield x-form-hidden x-form-field" value="2017-05-23 03:15:00" name="tv24" onblur="MODx.fireResourceFormChange();" type="hidden">
The data/time TV fields that are rendered on page load and are generated by this code:
Ext.onReady(function() {
var fld = MODx.load({
xtype: 'xdatetime'
,applyTo: 'tv24'
,name: 'tv24'
,dateFormat: MODx.config.manager_date_format
,timeFormat: MODx.config.manager_time_format
,dateWidth: 198
,timeWidth: 198
,allowBlank: true
,value: '2017-05-23 02:15:00'
,msgTarget: 'under'
,listeners: { 'change': { fn:MODx.fireResourceFormChange, scope:this}}
});
Ext.getCmp('modx-panel-resource').getForm().add(fld);
});
Everytime you run the above code a new div that houses the rendered input fields is generated with a generated id:
Unfortunately the actual ID's of the input fields are also incrementally generated. ie:
<input id="ext-comp-1185-date"
<input id="ext-comp-1186-date"