Embedded Systems LM5p-GSM, Product Manual

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2. -- verify that the requested object was found
3. if myobject then
4. myobject: write ( 52.12 , dt.float16 ) -- explicitly set data type to dt.float16 (2-byte
floating point)
5. end
Switch all binary objects tagged 'lights' off.
1. lights = grp.tag ( 'lights' )
2. lights: write ( false )
Group write to the specified group address and data type.
1. grp. write ( '1/1/1' , true , dt.bool ) -- write 1-bit 'on' to 1/1/1
2. grp. write ( '1/1/2' , 50 , dt.scale ) -- write 1-byte 50% to 1/1/2
6.2.11. Data type functions, data types
knxdatatype object provides data encoding and decoding between Lua and KNX data formats.
knxdatatype.decode(value, datatype)
Converts hex-encoded data to Lua variable based on given data type. Data type is specified
either as KNX primary data type (integer between 1 and 16) or a secondary data type (integer
between 1000 and 16000).Return values:

success — decoded data as Lua variable (type depends on data type), value length in
bytes

error — nil, error string
6.2.12. Data types
The following data types can be used for encoding and decoding of KNX data. Data
representation on Lua level and predefined constants (in bold) is given below:

1 bit (boolean) - dt.bool — boolean

2 bit (1 bit controlled) - dt.bit2 — number

4 bit (3 bit controlled) - dt.bit4 — number

1 byte ASCII character - dt.char — string

1 byte unsigned integer - dt.uint8 — number

1 byte signed integer - dt.int8 — number

2 byte unsigned integer - dt.uint16 — number

2 byte signed integer - dt.int16 — number

2 byte floating point - dt.float16 — number

3 byte time / day - dt.time — table with the following items:
o
day — number (0-7)