counsyl-pyads

This Python package contains a Python-only implementation of the AMS/ADS (Automation Device Specification) protocol for communicating directly with Beckhoff PLCs. No router is included or required. It is a fork of the pyads library by Christoph Wiedemann, with support for more data types (including arrays).

Installation

git clone git@github.com:counsyl/counsyl-pyads.git
cd counsyl-pyads
# consider making yourself a virtualenv
pip install -r requirements.txt
python setup.py install

PLC setup

Beckhoff PLCs won't accept connections from just anyone. The Twincat System Manager on the PLC contains a list of "routes" that define allowed clients. Perform the following steps to add the host where you plan to use counsyl_pyads to the list of routes:

1. Find your local IP address (ifconfig | grep inet should help), e.g. 192.168.4.13

• Dream up an Ams ID for your local machine. The Ams ID is a program identifier used by the ADS protocol. It's often IP address + .1.1 but any six byte sequence works, for example192.168.192.168.1.1. See the Beckoff Documentation for more information.
• Connect to the PLC computer and log in
• Open the System Manager (right click Twincat tray icon, then select System Manager)
• Navigate to SYSTEM - Configuration, Route Settings, then open the Static Routes tab
• Click Add. In the Add Route Dialog window, you need to fill out the bottom half of the form
  • Route Name (Target): Something descriptive to describe this route, consider including your name
  • AmsNetId: The Ams ID you dreamed up above
  • Transport Type: TCP/IP
  • Address Info: Your IP address
  • Select IP Address
  • Connection Timeout: 5
  • Target Route: Static
  • Remote Route: None

Usage

The script bin/twincat_plc_info.py should get you started with the basics. You can use it to query system information and a list of all varibles on a PLC.

twincat_plc_info.py 5.21.172.208.1.1:801 10.1.0.99 801 192.168.192.168.1.1:5555

This assumes that you have a PLC with Ams ID 5.21.172.208.1.1 available at IP 10.1.0.99 that is set up to accept connections from you (see PLC setup section above). Port 801 is default. 192.168.192.168.1.1:5555 is your arbitrary local Ams ID including a port that isn't used for anything.

Related Links

• AMS/ADS Protocol Overview
• ADS Command Documentation
• pyads library by Christoph Wiedemann