pyLSV2

This library is an attempt to implement the LSV2 communication protocol used by certain CNC controls. It's main goal is to transfer file between the application and the control as well as collect information about said files. Over time more and more functions where added which support gathering information from the control.

Most of this library is based on the work of tfischer73 and his Eclipse plugin found at his GitHub page. Since there is no free documentation beside the plugin, some parts are based purely on reverse engineering and might therefore be not correct.

As long as no encrypted communication is necessary and you are using Python 3.5 or newer, no additional librarys are necessary.

Please consider the dangers of using this library on a production machine! This library is by no means complete and could damage the control or cause injuries! Everything beyond simple file manipulation is blocked by a lockout parameter. Use at your own risk!

License

MIT License

Copyright (c) 2020 - 2023 drunsinn

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

News and Releases

check the github release page for information on the latest updates

Contributors

In chronological order:

• tfischer73
• drunsinn
• WouterElfrink
• kekec14
• Michal Navrátil
• PandaRoux8
• sazima
• manusolve
• NeeXoo
• Baptou88
• Md-aliy7
• npalmerDNX
• Andreas-strg
• oxbown

Usage

See lsv2_demo.py for a demonstration of some of the functions.

Since the whole protocol isn't documented there can always be problems with certain corner cases. Especially during file transfer a lot of stuff can go wrong. In case the control doesn't accept a command it returns an error. Some of these errors are checked internally but not everything is covered as of now. It is therefore best to check the last error with con.last_error. Every error consists of type and a status code. The enum LSV2StatusCode contains all known status codes.

Notes for upgrade to v1.xx

Notice: The change from 0.xx to 1.xx brought some major incompatible changes in regards to the API:

• raise the minimal required python version to 3.4 (for IronPython 3.4), future releases (1.1.x) will target 3.7 or higher!
• change of function names and parameters to better reflect their use
• change of return types from dict to data classes to reduce the dependency on magic strings These changes where made intentionally to make further development easier. See the demo script for an overview of the new API.

exemplary overview of the changes from v0.x to v1.x

Basic example without context manager

 import pyLSV2
 con = pyLSV2.LSV2("192.168.56.101")
 con.connect()
 print(con.versions.control)
 con.disconnect()

Basic example with context manager

 import pyLSV2
 with pyLSV2.LSV2("192.168.56.101") as con:
 ... con.connect()
 ... print(con.versions.control)

Accessing PLC data

To read values from the PLC memory you need to know the memory area/type and the memory address. There are two ways to read these values.

Reading via memory address

The following command reads 15 marker (bits) starting at address 32. This returns a list with 15 boolean values.

 con.read_plc_memory(32, pyLSV2.MemoryType.MARKER, 15)

See lsv2_demo.py for more examples.

The available memory areas and their python data type

Reading the values from the memory address takes the size of each memory type into account.

Reading via Data Path

The following command reads values from the control not via a memory address but via supplying a data access path. This will only work on iTNC controls! The advantage is that it also allows you to access tables like the tool table without reading the complete file.

 con.read_data_path('/PLC/memory/K/1')
 con.read_data_path('/TABLE/TOOL/T/1/DOC')

See lsv2_demo.py for more examples.

Note that reading values from memory does not take into account the actual size in the control memory. This leads to an offset between the values read with read_data_path and read_plc_memory. As a workaround you have to multiply the address value with the number of bytes the data type requires. The following example tries to show how this can be accomplished:

 for mem_address in [0, 1, 2, 4, 8, 12, 68, 69, 151, 300, 368]:
    v1 = lsv2.read_plc_memory(mem_address, pyLSV2.MemoryType.DWORD, 1)[0]
    v2 = lsv2.read_data_path("/PLC/memory/D/%d" % (mem_address * 4))
    assert v1 == v2

SSH Tunnel

Newer controls allow the use of ssh to encrypt the communication via LSV2. See ssh_tunnel_demo.py for an example on how to use the python library sshtunnel to achieve a secure connection.

Compatibility

Since there are a lot of different software versions and machine configurations out there it is hard to say if this library is compatible with all of them. Most testing has been done on programming stations but also with real hardware. Here is a list of versions that have been tested:

Programming Stations

1. some tests are failing and have not been analysed yet (screendump and rw_machine_parameter)
2. this control is not officially supported by any other Heidenhain tool but seems to be at least somewhat compatible

Machines

If you have tested it on one of your machines with a different software version, please let us know!

Tables

Included in this library is also functionality to work with Tables used by different NC Controls. This includes for example TNC controls as well as Anilam 6000i CNC. As these controls and there software versions use different table formats, it is also possible to dreive the format form an existing table and export the format to a json file.

See tab2csv.py for a demonstration on how to read a table and convert it to a csv file.

This script can also be used as a command line tool

 usage: tab2csv.py [-h] [--decimal_char DECIMAL_CHAR] [-d | -v] source
 
 command line script parsing table files
 
 positional arguments:
   source                table file to parse
 
 options:
   -h, --help            show this help message and exit
   --decimal_char DECIMAL_CHAR
                         override local decimal char
   -d, --debug           enable log level DEBUG
   -v, --verbose         enable log level INFO

Testing

To run the test you either need a machine or a programming station. The control has to be on and the PLC program has to be running. The IP address and timeout are set via command line parameters.

 pytest --address=192.168.56.103 --timeout=5

Minimum required Python version

The minimum required python version was checked with vermin.

 vermin --no-parse-comments .

The results indicate that pyLSV2 should work with python 3.6 and even with older versions if you install the packported modules argparse, enum and typing. While argpares is only used in the demo script the other two are necessary. Therefore it should be possible to use pyLSV2 with the current version of IronPython if you install these two modules.

Resources

• protocol.rst
• https://www.inventcom.net/support/heidenhain/read-tnc-plc-data
• https://www.inventcom.net/s1/_pdf/Heidenhain_TNC_Machine_Data.pdf
• https://www.yumpu.com/en/document/read/18882603/-f-heidenhain