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pyS7

pyS7 is a lightweight python library for data communication with Siemens PLCs. It partially implements the Siemens S7 Communication protocol over ISO-on-TCP (RFC1006), allowing for both data reading and data writing.

Niether the software nor the author are affiliated with Siemens in any way. S7-200, S7-300, S7-400, S7-1200 and S7-1500 are trademarks of Siemens AG.

Key Features:

  • Pure Python: No external dependencies for easy setup and platform compatibility.

  • User-friendly API, Intuitive and straightforward, offering simplicity and efficiency.

  • Multi-variable reading optimization: Enhanced support for simultaneous multi-variable reading, by packing together tags occupying adjacent areas of memory.

Disclaimer: Safety should always be your first priority when interacting with manufacturing machines. Therefore, when using this code, it is crucial to have a solid understanding of the machines and the tasks at hand. By choosing to use this code, you agree to assume all risks and accept responsibility for any damages or loss, including but not limited to data corruption, machine downtime, or other adverse effects.

Furthermore, please be aware that this code is under development. It is not battle-tested and changes to the API should be expected.

Install

pip install git+https://github.com/FiloCara/pyS7

Example

Reading data

from pyS7 import S7Client

if __name__ == "__main__":

    # Create a new 'S7Client' object to connect to S7-300/400/1200/1500 PLC.
    # Provide the PLC's IP address and slot/rack information
    client = S7Client(address="192.168.5.100", rack=0, slot=1)

    # Establish connection with the PLC
    client.connect()

    # Define area tags to read
    tags = [
        "DB1,X0.0",     # Read BIT 0 (first bit) of DB1
        "DB1,X0.6",     # Read BIT 7 (7th bit) of DB1
        "DB1,I30",      # Read INT at address 30 of DB1
        "M54.4",        # Read BIT 4 (fifth bit) in the merker (memento) area
        "IW22",         # Read WORD at address 22 in input area
        "QR24",         # Read REAL at address 24 in output area
        "DB1,S10.5"     # Read sequence of CHAR of length 5 starting at address 10 of DB1
    ]

    # Read the data from the PLC using the specified tag list
    data = client.read(tags=tags)

    print(data)  # [True, False, 123, True, 10, -2.54943805634653e-12, 'Hello']

Writing data

from pyS7 import S7Client, DataType, S7Tag, MemoryArea

if __name__ == "__main__":

    # Create a new 'S7Client' object to connect to S7-300/400/1200/1500 PLC.
    # Provide the PLC's IP address and slot/rack information
    client = S7Client(address="192.168.5.100", rack=0, slot=1)

    # Establish connection with the PLC
    client.connect()

    # Define area tags to write
    tags = [
        "DB1,X0.0",     # => S7Tag(MemoryArea.DB, 1, DataType.BIT, 0, 0, 1) - BIT 0 (first bit) of DB1
        "DB1,X0.6",     # => S7Tag(MemoryArea.DB, 1, DataType.BIT, 0, 6, 1) - BIT 7 (7th bit) of DB1
        "DB1,I30",      # => S7Tag(MemoryArea.DB, 1, DataType.INT, 30, 0, 1) - INT at address 30 of DB1
        "M54.4",        # => S7Tag(MemoryArea.MERKER, 0, DataType.BIT, 4, 4, 1) - BIT 4 (fifth bit) in the merker (memento) area
        "IW22",         # => S7Tag(MemoryArea.INPUT, 0, DataType.WORD, 22, 0, 1) - WORD at address 22 in input area
        "QR24",         # => S7Tag(MemoryArea.OUTPUT, 0, DataType.REAL, 24, 0, 1) - REAL at address 24 in output area
        "DB1,S10.5",    # => S7Tag(MemoryArea.DB, 1, DataType.CHAR, 10, 0, 5) - Sequence of CHAR (string) of length 5 starting at address 10 of DB1
        S7Tag(memory_area=MemoryArea.DB, db_number=5, data_type=DataType.REAL, start=50, bit_offset=0, length=3) # => Sequence of REAL of length 3 starting at address 50 of DB5 
    ]

    # Defines values to write
    values = [
        False,
        True,
        25000,
        True,
        120,
        1.2345,
        "Hello",
        (3.14, 6.28, 9.42)
    ]

    # Write data to the PLC using tags and values
    client.write(tags=tags, values=tags)

Look at the examples folder for more self-explanatory examples.

Supported variables

pyS7 uses a naming convention for PLC addresses, which slightly differs from the one used by Siemens Step7 and Tia portal. This convention is inspired by https://github.com/plcpeople/nodeS7/ and https://github.com/st-one-io/nodes7.

Please refer to the following table for getting the correct addresses and the supported types:

pyS7 Address Step7 Address Data type Description
DB2,X0.7 DB2.DBX0.7 Boolean Bit 7 (eighth) of byte 0 of DB 2
DB36,B2 DB36.DBB2 Number Byte 2 (0-255) of DB 36
DB102,C4 DB102.DBB4 String Byte 4 of DB 102 as a Char
DB10,I3 DB10.DBW3 Number Signed 16-bit number at byte 3 of DB 10
DB17,W4 DB17.DBW4 Number Unsigned 16-bit number at byte 4 of DB 17
DB103,DI3 DB103.DBD13 Number Signed 32-bit number at byte 3 of DB 103
DB51,DW6 DB51.DBD6 Number Unsigned 32-bit number at byte 6 of DB 51
DB21,R14 DB21.DBD14 Number Floating point 32-bit number at byte 14 of DB 21
DB102,S10.15 - String String of length 15 starting at byte 10 of DB 102
I3.0 or E3.0 I3.0 or E3.0 Boolean Bit 0 of byte 3 of input area
Q2.6 or A2.6 Q2.6 or A2.6 Boolean Bit 6 of byte 2 of output area
M7.1 M7.1 Boolean Bit 1 of byte 7 of memory area
IB10 or EB10 IB10 or EB10 Number Byte 10 (0 -255) of input area
QB5 or AB5 QB5 or AB5 Number Byte 5 (0 -255) of output area
MB16 MB16 Number Byte 16 (0 -255) of memory area
IC3 or EC3 IB3 or EB3 String Byte 3 of input area as a Char
QC14 or AC14 QB14 or AB14 String Byte 14 of output area as a Char
MC9 MB9 String Byte 9 of memory area as a Char
II12 or EI12 IW12 or EW12 Number Signed 16-bit number at byte 12 of input area
QI14 or AI14 QW14 or AW14 Number Signed 16-bit number at byte 14 of output area
MI14 MW14 Number Signed 16-bit number at byte 14 of memory area
IW24 or EW24 IW24 or EW24 Number Unsigned 16-bit number at byte 24 of input area
QW8 or AW8 QW8 or AW8 Number Unsigned 16-bit number at byte 8 of output area
MW40 MW40 Number Unsigned 16-bit number at byte 40 of memory area
IDI62 or EDI62 ID62 or ED62 Number Signed 32-bit number at byte 62 of input area
QDI38 or ADI38 QD38 or AD38 Number Signed 32-bit number at byte 38 of output area
MDI26 MD26 Number Signed 32-bit number at byte 26 of memory area
ID28 or ED28 ID28 or ED28 Number Unsigned 32-bit number at byte 28 of input area
QD46 or AD46 QD46 or AD46 Number Unsigned 32-bit number at byte 46 of output area
MD72 MD72 Number Unsigned 32-bit number at byte 72 of memory area
IR34 or ER34 IR34 or ER34 Number Floating point 32-bit number at byte 34 of input area
QR36 or AR36 QR36 or AR36 Number Floating point 32-bit number at byte 36 of output area
MR84 MR84 Number Floating point 32-bit number at byte 84 of memory area

License

This project is licensed under the terms of the MIT license. For more information, see the LICENSE file.