RSC Axioline Services

The Axioline component can be extended via interfaces for Axioline services. You can use one interface for acyclic communication (PdiRead, PdiWrite). This interface is available via the RSC protocol. The parameter data, diagnostic information, and status information (PDI = Parameters, Diagnostics and Information) of an Axioline device can be read or written with the RSC service. Acyclic communication is suitable for the exchange of data that does not recur cyclically.

The Axioline RSC services are only available to controllers of the PLCnext Control product family that support an Axioline local bus, e.g. the AXC F 2152.

Note: The execution of RSC services can take some time. For this reason, avoid direct calls from ESM tasks that are scheduled for real-time execution.


The IAcyclicCommunicationService RSC service in the Arp/Io/Axioline/Services namespace for acyclic communication makes the following methods available:

  • PdiRead
    Enables parameters, diagnostics and information of an Axioline device to be read
  • PdiWrite 
    Enables parameters, diagnostics and information of an Axioline device to be written
PdiResult PdiRead(const PdiParam& pdiParam, std::vector<uint8>& data)
PdiResult PdiWrite(const PdiParam& pdiParam, const std::vector<uint8>& data)

Parameters are necessary for executing PdiRead and PdiWrite. The PdiParam structure is used for transmitting the input parameters. The structure has the following elements:

Parameter Description
uint16 Slot Device number
uint8 Subslot Subdevice number
uint16 Index Object index
uint8 Subindex Object subindex

The return values are written to the PdiResult structure. The structure has the following elements:

Parameter Description
uint16 ErrorCode Error code
uint16 AddInfo Error code, further information

Data that is read (PdiRead) and data that is to be written (PdiWrite) is transferred in a type unit8 vector (data). A description of the data (maximum size, type, etc.) of the object description is available in the data sheet of the respective Axioline module.

You need the following headers to use the service. Include them via the #include command:

  • Arp\Io\Axioline\Services\IAcyclicCommunicationService.hpp
  • Arp\Io\Axioline\Services\PdiParam.hpp
  • Arp\Io\Axioline\Services\PdiResult.hpp

System-specific information on the Axioline F system is available in the PLCnext Engineer online help system, as well as in the user manuals Axioline F: System and installation (UM EN AXL F SYS INST) and Axioline F: Diagnostic registers and error messages (UM EN AXL F SYS DIAG).
These user manuals can be downloaded at PLCnext Control AXC F x152 product pages on the Phoenix Contact website, e.g. for AXC F 2152. Further information is also available in the data sheets of the respective Axioline I/O modules.




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• Published/reviewed: 2022-09-14 • Revision 046 •