diff --git a/python/plugins/processing/gui/NumberInputPanel.py b/python/plugins/processing/gui/NumberInputPanel.py
index c992acfe66d..8dee43a392f 100644
--- a/python/plugins/processing/gui/NumberInputPanel.py
+++ b/python/plugins/processing/gui/NumberInputPanel.py
@@ -39,6 +39,7 @@ from qgis.core import (QgsExpression,
                        QgsProcessingOutputVectorLayer,
                        QgsProcessingOutputRasterLayer,
                        QgsProcessingParameterFeatureSource,
+                       QgsProcessingModelAlgorithm,
                        QgsProcessingParameterRasterLayer)
 from qgis.gui import QgsExpressionBuilderDialog
 from processing.modeler.ModelerAlgorithm import ValueFromInput, ValueFromOutput, CompoundValue
@@ -82,28 +83,30 @@ class ModellerNumberInputPanel(BASE, WIDGET):
         values = self.modelParametersDialog.getAvailableValuesOfType(QgsProcessingParameterNumber, QgsProcessingOutputNumber)
         variables = {}
         for value in values:
-            if isinstance(value, ValueFromInput):
-                name = value.name
-                element = self.modelParametersDialog.model.inputs[name].param
-                desc = element.description
-            else:
-                name = "%s_%s" % (value.alg, value.output)
-                alg = self.modelParametersDialog.model.algs[value.alg]
-                out = alg.algorithm.outputDefinition(value.output)
-                desc = self.tr("Output '{0}' from algorithm '{1}'").format(out.description(), alg.description)
+            if isinstance(value, QgsProcessingModelAlgorithm.ChildParameterSource):
+                if value.source() == QgsProcessingModelAlgorithm.ChildParameterSource.ModelParameter:
+                    name = value.parameterName()
+                    element = self.modelParametersDialog.model.parameterDefinition(name)
+                    desc = element.description()
+                elif value.source() == QgsProcessingModelAlgorithm.ChildParameterSource.ChildOutput:
+                    name = "%s_%s" % (value.outputChildId(), value.outputName())
+                    alg = self.modelParametersDialog.model.childAlgorithm(value.outputChildId())
+                    out = alg.algorithm().outputDefinition(value.outputName())
+                    desc = self.tr("Output '{0}' from algorithm '{1}'").format(out.description(), alg.description())
             variables[name] = desc
         values = self.modelParametersDialog.getAvailableValuesOfType([QgsProcessingParameterFeatureSource, QgsProcessingParameterRasterLayer],
                                                                      [QgsProcessingOutputVectorLayer, QgsProcessingOutputRasterLayer])
         for value in values:
-            if isinstance(value, ValueFromInput):
-                name = value.name
-                element = self.modelParametersDialog.model.inputs[name].param
-                desc = element.description
-            else:
-                name = "%s_%s" % (value.alg, value.output)
-                alg = self.modelParametersDialog.model.algs[value.alg]
-                element = alg.algorithm.outputDefinition(value.output)
-                desc = self.tr("Output '{0}' from algorithm '{1}'").format(element.description(), alg.description)
+            if isinstance(value, QgsProcessingModelAlgorithm.ChildParameterSource):
+                if value.source() == QgsProcessingModelAlgorithm.ChildParameterSource.ModelParameter:
+                    name = value.parameterName()
+                    element = self.modelParametersDialog.model.parameterDefinition(name)
+                    desc = element.description()
+                elif value.source() == QgsProcessingModelAlgorithm.ChildParameterSource.ChildOutput:
+                    name = "%s_%s" % (value.outputChildId(), value.outputName())
+                    alg = self.modelParametersDialog.model.childAlgorithm(value.outputChildId())
+                    out = alg.algorithm().outputDefinition(value.outputName())
+                    desc = self.tr("Output '{0}' from algorithm '{1}'").format(out.description(), alg.description())
             variables['%s_minx' % name] = self.tr("Minimum X of {0}").format(desc)
             variables['%s_miny' % name] = self.tr("Minimum Y of {0}").format(desc)
             variables['%s_maxx' % name] = self.tr("Maximum X of {0}").format(desc)
@@ -125,21 +128,41 @@ class ModellerNumberInputPanel(BASE, WIDGET):
     def getValue(self):
         value = self.leText.text()
         values = []
+        #for param in self.modelParametersDialog.model.parameterDefinitions():
+        #    if isinstance(param, QgsProcessingParameterNumber):
+        #        if "@" + param.name() in value:
+        #            values.append(ValueFromInput(param.name()))
+        #for alg in list(self.modelParametersDialog.model.algs.values()):
+        #    for out in alg.algorithm.outputDefinitions():
+        #        if isinstance(out, QgsProcessingOutputNumber) and "@%s_%s" % (alg.modeler_name, out.name) in value:
+        #            values.append(ValueFromOutput(alg.modeler_name, out.name()))
+
         for param in self.modelParametersDialog.model.parameterDefinitions():
             if isinstance(param, QgsProcessingParameterNumber):
-                if "@" + param.name() in value:
-                    values.append(ValueFromInput(param.name()))
-        for alg in list(self.modelParametersDialog.model.algs.values()):
-            for out in alg.algorithm.outputDefinitions():
-                if isinstance(out, QgsProcessingOutputNumber) and "@%s_%s" % (alg.modeler_name, out.name) in value:
-                    values.append(ValueFromOutput(alg.modeler_name, out.name()))
+                if "@" + param.name() == value:
+                    return QgsProcessingModelAlgorithm.ChildParameterSource.fromModelParameter(param.name())
+
+        for alg in list(self.modelParametersDialog.model.childAlgorithms().values()):
+            for out in alg.algorithm().outputDefinitions():
+                if isinstance(out, QgsProcessingOutputNumber) and "@%s_%s" % (alg.childId(), out.name()) == value:
+                    return QgsProcessingModelAlgorithm.ChildParameterSource.fromChildOutput(alg.childId(), out.outputName())
+
         if values:
             return CompoundValue(values, value)
         else:
             return value
 
     def setValue(self, value):
-        self.leText.setText(str(value))
+        if isinstance(value, QgsProcessingModelAlgorithm.ChildParameterSource):
+            if value.source() == QgsProcessingModelAlgorithm.ChildParameterSource.ModelParameter:
+                self.leText.setText('@' + value.parameterName())
+            elif value.source() == QgsProcessingModelAlgorithm.ChildParameterSource.ChildOutput:
+                name = "%s_%s" % (value.outputChildId(), value.outputName())
+                self.leText.setText(name)
+            else:
+                self.leText.setText(str(value.staticValue()))
+        else:
+            self.leText.setText(str(value))
 
 
 class NumberInputPanel(NUMBER_BASE, NUMBER_WIDGET):
diff --git a/python/plugins/processing/modeler/ModelerParametersDialog.py b/python/plugins/processing/modeler/ModelerParametersDialog.py
index 7925d3d5ace..9c1db27cbaf 100644
--- a/python/plugins/processing/modeler/ModelerParametersDialog.py
+++ b/python/plugins/processing/modeler/ModelerParametersDialog.py
@@ -318,9 +318,6 @@ class ModelerParametersDialog(QDialog):
             if (isinstance(val,
                            QgsProcessingModelAlgorithm.ChildParameterSource) and val.source() == QgsProcessingModelAlgorithm.ChildParameterSource.StaticValue and not param.checkValueIsAcceptable(
                     val.staticValue())) \
-                    or (not isinstance(val,
-                                       QgsProcessingModelAlgorithm.ChildParameterSource) and not param.checkValueIsAcceptable(
-                        val))\
                     or (val is None and not param.flags() & QgsProcessingParameterDefinition.FlagOptional):
                 self.bar.pushMessage("Error", "Wrong or missing value for parameter '%s'" % param.description(),
                                      level=QgsMessageBar.WARNING)