secop_psi.entangle.AnalogInput: fix main value

when the unit of parameter 'value' is taken from tango, the
'$' units of other parameters are already replaced by the configured
value and are not updated. this change fixes this.

not yet tested on entangle, but a test with similar code works

Change-Id: I87ad112b0965b39bb204d6c3d1fc1de6d4e14f60
Reviewed-on: https://forge.frm2.tum.de/review/c/sine2020/secop/playground/+/29357
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Enrico Faulhaber <enrico.faulhaber@frm2.tum.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

secop/modules.py

@@ -461,8 +461,7 @@ class Module(HasAccessibles):
         if mainvalue:
             mainunit = mainvalue.datatype.unit
             if mainunit:
-                for pname, pobj in self.parameters.items():
-                    pobj.datatype.set_main_unit(mainunit)
+                self.applyMainUnit(mainunit)
 
         # 6) check complete configuration of * properties
         if not errors:
@@ -485,6 +484,11 @@ class Module(HasAccessibles):
     def __getitem__(self, item):
         return self.accessibles.__getitem__(item)
 
+    def applyMainUnit(self, mainunit):
+        """replace $ in units of parameters by mainunit"""
+        for pobj in self.parameters.values():
+            pobj.datatype.set_main_unit(mainunit)
+
     def announceUpdate(self, pname, value=None, err=None, timestamp=None):
         """announce a changed value or readerror"""