chore: add callback PV to template

templates/service/{{service_id}}-{{service_name_lower}}/current/app/src/AGEBD-SERVICE-{{service_name_upper}}.py.jinja

@@ -43,7 +43,9 @@ class PVs(BasePVs):
 
         # TODO: class attribute names usually lowercase
         # usually it is advisable to trigger the mainloop of a service on changes of certain PVs:
-        self.CallbackPV = PV("...", auto_monitor=dbr.DBE_VALUE)
+        self.CallbackPV = PV(
+            "AGEBD-{{ service_name_upper }}:CALLBACK", auto_monitor=dbr.DBE_VALUE
+        )  # TODO: ok?
 
 
 class Service(BaseService[PVs]):
@@ -77,13 +79,17 @@ class Service(BaseService[PVs]):
         #######################################################################################
         # here goes all the code that your service
         # is supposed to be running in any case, e.g.,
+
         # update some pvs/vals
-        self.pvs.my_pv1.put("MY_PV1 value")
-        self.pvs.my_pv2.put("MY_PV2 value")
+        # self.pvs.my_pv1.put("MY_PV1 value")
+        # self.pvs.my_pv2.put("MY_PV2 value")
+
+        # get some pvs/vals
         self.val1 = self.pvs.my_pv1.get()
         self.val2 = self.pvs.my_pv2.get()
         print(self.val1)
         print(self.val2)
+
         # maybe sleep to limit the update loop execution rate
         sleep(1)
         #######################################################################################

templates/service/{{service_id}}-{{service_name_lower}}/current/ioc/{{service_name_upper}}.template

@@ -24,4 +24,14 @@ record(bo, "$(DEVICE):BO") {
     field(OSV,  "NO_ALARM")
     field(VAL,  "1")
     field(PINI, "YES")
+}
+
+# TODO: ok?
+record(bo, "$(DEVICE):CALLBACK") {
+    field(DESC, "Callback PV to listen to for changes")
+    field(ASG,  "READONLY")
+    field(ZSV,  "MINOR")
+    field(OSV,  "NO_ALARM")
+    field(VAL,  "1")
+    field(PINI, "YES")
 }