Protocols and Field Devices

Siemens S7

• Absolute addressing
• TIA, symbolic addressing
• S7 300/400 and 1200 & 1500

Supported Data Types

The supported data types depend on the addressing mode (absolute or symbolic). You can find them in the following table.

Data type	In Edge (read only)	Supported by PLC
Edge VarType	Edge InfluxType	Bits	Symbolic	Absolute	S7-300/400	S7-1200	S7-1500
Binary numbers
S7_Bool	FLOAT	1	✔	✔	✔	✔	✔
S7_Byte	FLOAT	8	✔	✔	✔	✔	✔
S7_Word	FLOAT	16	✔	✔	✔	✔	✔
S7_DWord	FLOAT	32	✔	✔	✔	✔	✔
S7_LWord	FLOAT	64	✔	✔			✔
Integers
S7_SInt	FLOAT	8	✔	✔		✔	✔
S7_Int	FLOAT	16	✔	✔	✔	✔	✔
S7_DInt	FLOAT	32	✔	✔	✔	✔	✔
S7_USInt	FLOAT	8	✔	✔		✔	✔
S7_UInt	FLOAT	16	✔	✔		✔	✔
S7_UDInt	FLOAT	32	✔	✔		✔	✔
S7_LInt	FLOAT	64	✔	✔			✔
S7_ULInt	FLOAT	64	✔	✔			✔
Floating-point numbers
S7_Real	FLOAT	32	✔	✔	✔	✔	✔
S7_LReal	FLOAT	64	✔	✔		✔	✔
Times
S7_S5Time	STRING	16	✔	✔	✔		✔
S7_Time	STRING	32	✔	✔	✔	✔	✔
FLOAT
(millisec.)	❌	❌
S7_LTime	STRING	64	✔	✔			✔
FLOAT
(nanosec.)	❌	❌
Date and time
S7_Date	STRING	16	✔	✔	✔	✔	✔
FLOAT
(days)	❌	❌
S7_Time_Of_Day	STRING	32	✔	✔	✔	✔	✔
FLOAT
(millisec.)	❌	❌
S7_LTOD	STRING	64	✔	✔			✔
FLOAT
(ticks)	❌	❌
S7_Date_And_Time	STRING	64	✔	✔	✔		✔
S7_LDT	STRING	64	✔	✔			✔
S7_DTL	STRING	96	✔	✔		✔	✔
Characters
S7_Char	STRING	8	✔	✔	✔	✔	✔
S7_WChar	STRING	16	✔	✔		✔	✔
S7_String	STRING	n+2 Bytes	✔	✔	✔	✔	✔
S7_WString	STRING	n+2 Words	✔	✔		✔	✔
Array
S7_Array			✔	✔ Individual access to each element via its specific address	✔ Max. dimensions: 6
Max. number of bytes: 32,767	✔ Max. dimensions: 6
Max. number of bytes: 65,535	✔ Max. dimensions: 6
Max. number of bytes: 16,777,216
Pointers
Pointer		48	❌	❌	✔		✔
Any		80	❌	❌	✔		✔
Variant		0	❌	❌		✔	✔

Manual address entry

If measured variables are entered manually via the UI or imported via a CSV file, the following points must be observed when specifying addresses.

Absolute addressing

For absolute-addressed data access, the address schema must follow the common, fully qualified schema consisting of data block number, operand, and byte/bit offset.

Structure: DB<Nr>.DB<B|W|D|X><ByteOffset>.<BitOffset>; noting:

• The operand type described by DBB, DBD, DBX, or DBW can currently be used arbitrarily; it could be set to DBB for all data types as well (it merely serves the familiar readability for the PLC programmer)
• The bit offset is optional and may be omitted (including the separating period) as needed
• Spaces must be removed

Examples:

• DB9.DBX200.2 Addresses the second bit of byte 200 in data block no. 9
• DB30.DBW558 Addresses byte 558 of data block no. 30

Symbolic addressing

For symbolic-addressed data access, the address is composed hierarchically from the program structure and groups, separated by a period. It always begins with the two group elements PLC (not the device name such as PLC_1!) and Blocks. Note the following:

• If group elements or variables contain a period, that address part must be enclosed in double quotation marks (ASCII code 0x22)
• If group elements or variables contain a double quotation mark, that address part must be enclosed in double quotation marks and the contained quotation mark must additionally be doubled
• Case sensitivity must be observed
• Certain special characters also require escaping with double quotation marks (e.g.: <>[ ] . { } )

Examples:

• PLC.Blocks.TestDB.MyFunkyVariable Addresses a variable named MyFunkyVariable in the data block named TestDB (directly subordinate to the main structure)
• PLC.Blocks.TestDB."My.Funky.Struktur".MyFunkyVariable Addresses a variable named MyFunkyVariable in a UDT instance My.Funky.Struktur in the data block named TestDB (directly subordinate to the main structure)
• PLC.Blocks.TestDB."My""Funky""Struktur"."My""Funky""Variable" Addresses a variable named My"Funky"Variable in a UDT instance My"Funky"Struktur in the data block named TestDB (directly subordinate to the main structure)
• PLC.Blocks.TestDB.TestArray.MyFunkyElement[28] Addresses the 28th element of the one-dimensional array TestArray in the data block named TestDB (directly subordinate to the main structure)
• PLC.Blocks.TestDB.TestArray.MyFunkyElement[2,1,28] Addresses element no. [2,1,28] of the multi-dimensional array TestArray in the data block named TestDB (directly subordinate to the main structure)

Caution

⚠ Invalid address entries, which frequently occur with manual input, prevent proper data access! By using the import function, this source of error is eliminated — variables are correctly formatted and escaped when transferred into the Edge structure.

Modbus TCP

Function	Comment
Supported access methods	READ_COIL, READ_DISCRETE_INPUT, READ_INPUT_REGISTER, READ_HOLDING_REGISTER
Supported data types	BOOLEAN*, INT16, UINT16, INT32, UINT32, INT64, UINT64, FLOAT, DOUBLE, STRING** *Boolean is only supported for bit-level access methods (read coils, read discrete input). ** The STRING data type is set to 8 characters by default. If a different number of characters is required, please contact support.
Slave ID
(Modbus RTU)	For Modbus RTU, the “Slave ID” can be specified. Default = 1
Byte order
(endianness)	Big-endian*, little-endian* (default) * For data types larger than 16 bits (INT32, UINT32, INT64, UINT64, FLOAT, DOUBLE, STRING). Defines which REGISTER (not bytes) contains the most significant bit. Byte order is an optional configuration parameter that cannot currently be configured in the UI. If a deviation from the default is required, please contact support.