Overview of S7 protocol¶

The following image shows the data source input window for the S7 protocol:

Overview of S7 protocol

You can choose between automatic and manual connection type.

Automatic: This mode tries to find slot and rack number automatically.
Manual: In this mode you can enter the rack and slot number manually.

For S7 connection type the PG type-programmer-type-connection is used thus you will not be able to make use of PG connection.

Note

Symbolic access

This solution does not allow full symbolic access.

Requirements for S7-1200 and S7-1500¶

Put/Get communication must be permitted (can be found e.g. S7-1500 -> Properties -> Protection & Security -> Connection mechanisms).
The “Optimized block access” of the data blocks that you want to read must be deactivated (can be found in the data block properties).

Address format examples¶

Detailed examples:

Example address format DB15.DBX6.3:

DB15.DBX6.3¶

Area indicator			Data type	Offset address
DB15	-	DB	X	6	-	3
Datablock address	Separator	Datablock	Bool	Offset Byte	Separator	Offset Bit
			Reads 3^rd bit of byte 6 of datablock 15

Example address format IW10:

IW10¶

Area indicator	Data type	Offset address
I	W	10
Process Input	Word	Offset Byte
	Reads a word of input starting from offset 10

Overview¶

If you want to read data out of other areas, please replace “DB15.DB“ from the examples with the area indicator from the list below:

Attention: only certain address examples work with Inputs and Outputs (see²⁾).

S7		MindSphere
Data type	Length/unsigned/signed	Data type (length)	Address example	Description
Bool	1 bit	BOOLEAN (1 bit)	DB15.DBX6.3²⁾	Reads 3^rd bit of byte
				6 of datablock 15
Byte	1 byte / unsigned	INT (4 bytes) LONG	DB15.DBB4²⁾	Reads an unsigned byte
USInt		(8 bytes) DOUBLE	DB15.DBBYTE4	starting from offset 4
		(8 bytes)¹⁾		out of datablock 15.
SInt	1 byte / signed
Char	1 byte / signed		DB15.DBCHAR6	Reads a char starting
				from offset 6 of
				datablock 15.
Word	2 bytes / unsigned		DB15.DBW10²⁾	Reads an unsigned word
UInt			DB15.DBWORD10	starting from offset 10
				of datablock 15.
Int	2 bytes / signed		DB15.DBINT12	Reads a signed integer
				starting from offset 12
				out of datablock 15.
DINT	4 bytes / signed		DB15.DBDINT28	Reads a signed double
				integer starting from
				offset 28 of datablock 15.
DWord	4 bytes / unsigned	LONG (8 bytes)	DB15.DBDW24²⁾	Reads an unsigned double
UDInt		DOUBLE (8 bytes)¹⁾	DB15.DBDWORD24	word starting from offset
				24 of datablock 15.
Real	4 bytes / signed	DOUBLE (8 bytes)	DB15.DBD32²⁾	Reads a floating-point
			DB15.DBREAL32	number starting from
				offset 32 of datablock 15.
String	Length of variable,	STRING	DB15.DBSTRING10	The maximum string length
	max. 254 bytes	(max. 254 bytes)		(Byte10) is read first.
				Then the number of bytes
				that Byte10 indicates are
				number read. After that
				the of bytes that Byte11
				indicates are extracted
				from the byte array that
				is the result of second
				read operation.
				For example:
				- (Byte10)- 30
				- (Byte11)-4
				- (Byte12-Byte15)-TEST
				First read result: 30
				Second read result: 4TEST
				We will extract TEST from
				the second read result by
				considering Byte11's value.
String	Min. 100 bytes ,		DB15.DBSTRING10,100	Reads 100 bytes of string
	max. 254 bytes			starting from offset 10.

¹⁾ When DOUBLE is used for integers, they are converted to a floating-point number.

²⁾ For the areas Inputs and Outputs only certain address examples work.

Note

Signed values

If you want to read a signed value, you have to use the respective signed datablock.

Example:

DB1831.DBW508 is unsigned. You can use DB1831.DBINT508 instead.

Area Types¶

S7 datapoint addresses must contain an area type.

Area indicator	Area types	Description
C	Counter	Reads Counter value of hardware.
DB	Datablock	Reads datablock value from hardware.
DI	Instance Data	Reads data directly from hardware.
I	Process Input	Reads Input value of Process image.
M	Memory	Reads Memory value of hardware.
PI	Peripheral Input	Reads Input value directly from hardware.
PQ	Peripheral Output	Reads Output value directly from hardware.
Q	Process Output	Reads Input value of Process image.
T	Timer	Reads Timer value of hardware.

Area Number¶

S7 datapoint addresses must contain area number.

E.g.: DB10 (10. datablock)

Data Types¶

The following table shows the MindSphere data types:

MindSphere data types:

Data type	Length	Date range: From	Data range: To
BOOLEAN	1 bit	True	False
INT	4 bytes	−2147483648	2147483647
LONG	8 bytes	−9223372036854775808	9223372036854775807
DOUBLE	8 bytes	-9.9999999999999999999999999999999999999E+125	9.9999999999999999999999999999999999999E+125
STRING	1-255 bytes

The following table shows the S7 data types:

S7 data types:

Data type	Length	Date range: From	Data range: To
Bool	1 bit	True	False
Byte (unsigned)	1 byte	0	255
Word (unsigned)	2 bytes	0	65.535
DWord (unsigned)	4 bytes	0	4294967295
Char (signed)	1 byte	−128	127
Int (signed)	2 bytes	−32768	32767
DINT (signed)	4 bytes	−2147483648	2147483647
Real	4 bytes	±1,18e-38	±3.40e+38
String	1- 254 bytes

Offset¶

Variable types must have an offset. Offset is the starting byte number.

E.g. DW4 (a double word starting from byte 4)

String¶

Data type	Length in bytes	Format
STRING[n] or STRING	n+2	ASCII character of any length. n specifies the length of the character string. A maximum length of 254 characters is permitted. If no length is specified, the default setting is 254 characters.

Data type	Examples of format used
STRING[2]	'AB'
STRING[55]	'The character string can consist of up to 55 characters'

Note

You must enclose your character string in single quotation marks.

The following example shows the byte order when specifying the datatype STRING[4] with the output value 'AB'.

Datatype string

* Tod


TIME_OF_DAY (Time)	32	Time is in steps of 1 ms	TOD#0.0.0.0 to TOD#23:59:59.999	L TOD#1:10:3.3
				L TIME_OF_DAY#1:10:3.3

* Time

Returns milliseconds.

Format:

The DT (DATE_AND_TIME) datatype saves the information on date and time of day in BCD format.

The following table shows the properties of datatype DT:

Length (bytes)	Format	Range of values	Example of value input
8	Date and time (year-month-day)

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Last update: May 19, 2022