ADS (Automation Device Specification)


The ADS (automation device specification) describes a device-independent and fieldbus independent interface for communication between Beckhoff automation devices running TwinCAT and other devices implementing this interface. Source (accessed 7 August 2022)

Specifcation for ADS devices: Source (accessed 7 August 2022)

Structure AMS/TCP Packet

ADS (Automation Device Specification) is the TwinCAT communication protocol that specifies the interaction between two ADS devices. For example, it defines what operations can be executed on another ADS device, what parameters are necessary for that and what return value is sent after execution.

AMS (Automation Message Specification) specifies the exchange of the ADS data. A major component of the communication protocol is the AmsNetId. This is specified in the AMS/ADS package for the source and target device. An ADS device can be explicitly addressed using the AmsNetId. Source (accessed 7 August 2022)

Connection String Options

Name Value Description




ADS Protocol

Maven Dependency


Default Transport:


Supported Operations





setTargetAmsNetId(AmsNetId targetAmsNetId)




Defaults to 48898

Data array Size Description

AMS/TCP Header

6 bytes

contains the length of the data packet.

AMS Header

32 bytes

The AMS/TCP-Header contains the addresses of the transmitter and receiver. In addition the AMS error code , the ADS command Id and some other information.

ADS Data

n bytes

The ADS data range contains the parameter of the single ADS commands. The structure of the data array depends on the ADS command. Some ADS commands require no additional data.

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