dataCombo parameters value

There are two good approaches to this, both relying on an onchange event handler on the first dataCombo.

The first, simpler solution would be to just have an onchange event handler set the value directly:

<dataCombo id="Grupo_Producto" name="Grupo_Producto" dataBinding="bdGrupo" size="40" 
 label="(*) Grupo" dropdownWidth="400" dropdownHeight="100" loadingMessage="Cargando..."
 columnHeaders="Codigo, Nombre"
 queryClass="Innova.CL.Core.BD.Configuracion.Operacional.Grupo" queryName="obtieneGrupoProd"
 sqlLookup="SELECT Nombre FROM Innova_CL_Core_BD_Configuracion_Operacional.Grupo Where ID = ?"
 onchange="zen('Linea_Producto').setProperty('parameters',1,zenThis.getValue());"
 > 
</dataCombo>

However, if you have multiple components on the page that depend on the current value of Grupo_Producto, it might be simpler to use a property of the page that has the value of the component copied to it when that value changes. This is handy because you can reference the value in a Zen expression, e.g., #(%page.GrupoProducto)#, rather than needing to copy the same value to lots of places. Here is an example with two dataCombos in the SAMPLES namespace:

Class DC.Demo.ComboBox Extends %ZEN.Component.page
{

Property homeState As %ZEN.Datatype.string;

XData Contents [ XMLNamespace = "http://www.intersystems.com/zen" ]
{
<page xmlns="http://www.intersystems.com/zen">
<dataCombo id="homeState" label="State"
sql="select distinct Home_State from Sample.Person order by Home_State"
onchange="zenPage.dataComboChanged(zenThis)"
/>
<dataCombo id="homeCity" label="City"
sql="select distinct %exact Home_City from Sample.Person where Home_State = ? order by Home_City">
<parameter value="#(%page.homeState)#" />
</dataCombo>
</page>
}

ClientMethod dataComboChanged(component) [ Language = javascript ]
{
    // Update the page property's value.
    // Note: page property and component ID don't necessarily need to match, but it's convenient if they do.
    // (Imagine a cascade of dataCombos with dependent values.)
    zenPage.setProperty(component.id,component.getValue());
    
    // Possibly also call refreshContents() on components referencing properties that may have changed,
    // and/or clear values that may have been invalidated by the change.
    // dataCombo does not need this, but other components (e.g., tablePane) would.
}

}