some work on developer guide doc page

Author: Jan C

docs/developer_guide.md

@@ -7,33 +7,94 @@ Following sections will appear some day:
 
 Entities are declared in the plugin_xxx.py files.
 Each type of entity may support different attributes.
+The entity types are also briefly documented in the const.py file.
 
 ### Common attributes for all entities
 
+Most of the attributes are optional or have a meaningfull default value
+
+ * _allowedtypes_: int = 0  # overload with ALLDEFAULT from plugin
+ * _register_
+ * _blacklist_: # None or list of serial number prefixes like ["XRE",] for which the entity will not appear
+
 To be completed
 
 ### Attributes for sensor entities:
 
-To be completed
+To be documented:
+
+* _scale_
+* _read_scale_exceptions_
+* _read_scale_
+* _rounding_
+* _register_type_: REGISTER_HOLDING, REGISTER_INPUT or REG_DATA
+* _unit_: int = None  #  optional for WRITE_DATA_LOCAL e.g REGISTER_U16, REGISTER_S32 ...
+* _internal_
+* _newblock_: the system automatically builds blocks of registers that will be polled together, a newblock attribute indicates that a newblock should start at this address. Do not use too many newblock statements as the polling cycle may contain too many operations.
+* _value_function_
+* _sleepmode_: either SLEEPMODE_LAST (default), SLEEPMODE_ZERO or SLEEPMODE_NONE 
+* _ignore_readerror_
+* _value_series_
+* _min_value_
+* _max_value_
 
 ### Attributes for number entities:
 
-To be completed
+To be documented:
+
+* _read_scale_exceptions_: list = None
+* _read_scale_: float = 1
+* _fmt_: str = None
+* _scale_: float = 1
+* _state_: str = None
+* _max_exception_s: list = None  #  None or list with structue [ ('U50EC' , 40,) ]
+* _min_exceptions_minus_: list = None  # same structure as max_exceptions, values are applied with a minus
+* _write_method_: int = WRITE_SINGLE_MODBUS  # WRITE_SINGLE_MOBUS or WRITE_MULTI_MODBUS or WRITE_DATA_LOCAL
+* _initvalue_: int = None  # initial default value for WRITE_DATA_LOCAL entities
+* _unit_: int = None  #  optional for WRITE_DATA_LOCAL e.g REGISTER_U16, REGISTER_S32 ...
+* _prevent_update_: bool = (
+        False  # if set to True, value will not be re-read/updated with each polling cycle; only when read value changes
 
 ### Attributes for select entities:
 
-To be completed
+To be documented:
+    
+* _option_dict_: dict = None
+* _reverse_option_dict_: dict = None  # autocomputed - do not specify
+* _write_method_: int = WRITE_SINGLE_MODBUS  # WRITE_SINGLE_MOBUS or WRITE_MULTI_MODBUS or WRITE_DATA_LOCAL
+* _initvalue_: int = None  # initial default value for WRITE_DATA_LOCAL entities
 
 ### Attributes for button entities:
 
-To be completed
+To be documented:
+
+* _command_
+* _write_method_
+* _autorepeat_ : see separate documentation on autorepeat buttons
+
+### Attributs for switch entities:
+
+To be documented:
+
+* _register_bit_: int = None
+* _write_method_: int = WRITE_SINGLE_MODBUS  # WRITE_SINGLE_MOBUS or WRITE_MULTI_MODBUS or WRITE_DATA_LOCAL
+* _sensor_key_: str = None  # The associated sensor key
+* _initvalue_: int = None  # initial default value for WRITE_DATA_LOCAL entities
+
+
+
+## Scan groups for differentiated polling
+Some inverter plugins use different scan groups (to differentiate between slowly changing sensor entities and entities that are updated frequently?)
+To be documented 
+
 
 
 ## Autorepeat mechanism for buttons
 
 A button can have the attribute autorepeat, an attribute that specifies the entity_key of the entity that holds the duration over which the button press will be repeated automatically.
 If a button has the autorepeat attribute autorepeat, the button declaration must also have a value_function attribute. The specified value function will be called for each autorepeat loop interation.
 The meaning of the parameters of a button value function is:
+
 * initval: either BUTTONREPEAT_FIRST, BUTTONREPEAT_LOOP, BUTTONREPEAT_POST
   * BUTTONREPEAT_FIRST indicates it is the first call, usually a manual button press
   * BUTTONREPEAT_LOOP indicates subsequent autorepeated calls
@@ -45,7 +106,9 @@ In its current form, the function should return a dictionary containing followin
  * action: the modbus type of write to be executed: currently only MODBUS_WRITE_MULTI is suppored, but the other writes can be easily added later.
  * register (optional): if not specified, the register address for the autorepeat button will be used
  * data: a list of tuples [ (entity_key, value,), ....] that represents the payload of a write_multiple command that starts at the modbus register addres. Instead of the entity_key_name, a register type can also be specified like REGISTER_U16. The payload should not contain the button's entity itself, just the data that needs to be added in the write_multiple scenario.
+
 In the future, the return value may be extended to allow other types of writes (to different addresses).
 The system will automatically compute the length of the write_multiple payload to be executed.
 
 The autorepeat value_function is called once for every polling loop, so it is up to the value function to reduce the number of interactions if desired. Currently, the value_function cannot pass data to the next polling cycle's value_function's call. This could be enhanced as using global variables is not considered a best practice (may fail in case of multiple inverters/hubs). Storing this data in the descr._hub object may be better, but it is still not very transparent.
+____