Beckhoff ADS (experimental)

This protocol is experimental. It has been tested on CX7000 and CX8190 (TwinCAT 3) and CX1020 (TwinCAT 2); behaviour on other controllers may differ.

This input reads variables from Beckhoff PLCs over ADS by symbol name, either as change notifications pushed by the PLC or as interval polling. It works with TwinCAT 2 and TwinCAT 3, runs from a virtual machine or a container, and can register its own route on the PLC.

This input reads symbols only: named variables such as GVL_ProcessData.nMasterCycleCounter. Direct addresses (%MB100) are not supported.

Where to go

Page	For
Quick start	Getting first values out of a PLC, step by step
How it works	ADS, AMS NetIDs and routes; read this once and the settings explain themselves
Configuration	Every setting, with complete examples
Symbols and metadata	How to address symbols, and what each message carries
Networking	Containers, VPNs, NAT, and creating routes by hand
Troubleshooting	Symptoms, causes, and what the log lines mean

Prerequisites

Have these ready before you start. Everything else has a working default.

	What you need	How to check
PLC address	The IP address of the PLC, reachable from wherever this runs	ping <plc-ip>
ADS port open	TCP 48898 to the PLC	nc -z -w3 <plc-ip> 48898
Route port open	UDP 48899, only if the plugin should register its own route	Blocked UDP means creating the route by hand instead
PLC credentials	An administrator user on the PLC, only for automatic route registration	The same login you would use in TwinCAT to add a route
This client's address	The address the PLC will see this client as, needed for hostIP	Usually the VM's IP on the PLC network. Behind a container boundary, VPN or NAT it is something else: see Networking
Symbol names	The full name of each variable, e.g. GVL_ProcessData.nMasterCycleCounter	Read them from the PLC project in TwinCAT
A running PLC runtime	The runtime must be in RUN, not CONFIG	A stopped runtime accepts the connection and serves nothing

Two limits worth knowing up front:

• Beckhoff recommends no more than 550 notifications per device. Above that, read in fewer, larger pieces (a struct instead of its members) or switch to readType: interval, which reads with sum commands.

• A PLC serves one connection per client address. A second client from the same address displaces the first. That second client can be another instance of this input, or an engineering station behind the same NAT gateway.