Profisafe Device Identification: F-Parameters

This topic contains the following sections:

General Information on F-Adresses: F_Source_Add and F_Dest_Add

In a Profisafe network, the Safety PLC, which acts as F-Host, and the safety-related devices (F-Devices), are identified by means of F-addresses:

The F-Host in a Profisafe network is uniquely identified by its source address: F_Source_Address. This address is used for the communication relationships to all safety nodes (F-Devices) which are assigned to this F-Host.
Consider the special case that a Safety PLC is used as both F-Host and F-Device.
Set the source address of the F-Host in PLCnext Engineer as follows:
1. In the PLANT, double-click the controller node and open the 'Safety Parameters' editor.
2. In the 'Safety Parameters' editor enter the 'F_Source_Add'.
  Value range: unique decimal value between 0 and 65535.
Example:
Each safety-related device is identified by a destination address F_Destination_Address, or F_Dest_Add.
Consider the special case that a Safety PLC is used as both F-Host and F-Device.
Set the source address of each F-Device in PLCnext Engineer as follows:
1. In the PLANT, expand the safety-related Profisafe device under the 'Profinet' node and double-click the submodule node. Open the 'Safety Parameters' editor.
2. In the 'Safety Parameters' editor enter the 'F_Dest_Add'.
  Value range:
  - For safety modules from Phoenix Contact, you can set Profisafe decimal destination addresses from 1 to 999, maximum.
  - For safety modules from other manufacturers, destination addresses from 1 to 65534 are supported.
  PLCnext Engineer checks the validity (value range and uniqueness) of the entered value directly while editing.
  Example:

In applications with several F-Hosts, each F-Host and its assigned F-Devices are considered as island.

The maximum number of connectable F-Devices per F-Host depends on the host type.
The RFC 4072S controller, for example, supports a maximum of 300 F-Devices.

Note
Observe the limitations described in the respective user manual, for example, regarding the maximum length of safety-related input or output messages.

Note
F-Parameters and I-Parameters - Term definition
The address parameters (source address of the F-Host and F-Device destination addresses) are collectively referred to as F-Parameters. Within a Profisafe network, these addresses must be unique.
The term I-Parameters refers to the data record consisting of the safety logic and the safety-related channel parameters (input/output parameters). This means, I-Parameters specify the configured safety function and the channel parameters of the devices concerned. In the 'Safety Parameters' editor of the respective device in PLCnext Engineer, they are listed in channel-related parameter categories.

Safety PLC acts as F-Host and F-Device

Consider the following scenario:

Note
This scenario is only possible for particular controller types.

The Safety PLC (no. (1) in the figure) acts as F-Host of the Profisafe network you are currently developing in your PLCnext Engineer solution (2). Therefore, it needs an F_Source_Address for its own Profisafe network.
At the same time, the Safety PLC (1) in your solution (2) acts as F-Device in a superimposed Profisafe network (3). This superimposed Profisafe network has its own F-Host (4) and possibly further F-Devices (5) besides your Safety PLC (in further subordinate networks). In this case, your Safety PLC also needs an F_Destination_Address as Profisafe client of the superimposed network.

Only in this scenario, the following applies:

The Safety PLC in your solution needs both an F_Source_Address and an F_Destination_Address.
Both addresses must be defined in the 'Safety Parameters' editor as described above.
The F_Destination_Address of the Safety PLC may be the same as the F_Destination_Address of another F-Device used in your solution. This is allowed as the addresses belong to different Profisafe networks.
The F_Destination_Address of the Safety PLC may be the same as its F_Source_Address. This is allowed as the addresses belong to different Profisafe networks.
The safety application you are developing in your solution relates to the current Profisafe network in which the Safety PLC is the F-Host.
The communication between the superimposed Profisafe network and the Safety PLC (as F-Device) is done using special system variables. Currently, 16 SAFEBYTE variables can be exchanged between the upstream F-Host and the Safety PLC in your solution:
- FDEV_IN0 to FDEV_IN7 can be written by the F-Host of the superimposed network and read by the Safety PLC in your solution.
- FDEV_OUT0 to FDEV_OUT7 can be written by your Safety PLC and read by the F-Host of the superimposed network.
These safety-related system variables are available in the Data List of the 'Safety PLC'. Here, they can be assigned to global variables of the standard controller in order to read them in the standard application.

Dynamic assignment of the F_Dest_Add via system variables

You can use system variables to assign an F-Device an F_Destination_Address (F_Dest_Add) dynamically, i.e. from within the safety-related application program (instead of using the fixed F_Dest_Add set in the 'Safety Parameters' editor of the controller node in the PLANT, as described above). This allows an F-Device to be dynamically subordinated to another F-Host. A possible scenario for this is the transfer of an AGV (Automated Guided Vehicle) to a new driving area.

Setting the F_Dest_Add at runtime using system variables is possible with both Profisafe profile version 2.4 and version 2.6.

The set of variables available for this purpose is described in the topic "System Variables", section "F-Device-related System Variables for Dynamic F_Dest_Add Assignment".

Please note the following points regarding the dynamic programmatic assignment of the F-Device address:

The transfer and (re)configuration of a changed F_Dest_Add of the local F-Device instance can only take place in the Stop state of the F-Device. Therefore, the Profinet connection of the local F-Device to the superimposed F-Host must be disconnected. Profisafe communication to the superimposed F-Host is therefore no longer possible.
The local F-Device instance is then explicitly stopped and the state machine of the local F-Device is completely reinitialized.
The application must then explicitly allow the Profinet connection to the new superimposed F-Host again. The Profinet connection of the local F-Device to the F-Host is then established and the F-Device receives the new F-Parameter set from the new F-Host and parameterizes itself completely. Finally, the Profisafe point-to-point communication to the superimposed F-Host is established/synchronized. A communication error in the higher-level safety application may need to be acknowledged.

Note
The error-correcting measures for incorrect addressing of the Profisafe profile (according to the Profisafe Profile 2.61) are only effective if all F-Hosts in the domain/cell have been assigned a unique F-Source address.

WARNING

Unintended machine operation

Make sure that for the duration of the dynamic F_Dest_Add assignment (during which the relevant F-Device is not available), no risk or hazardous situation can arise from the downtime of the F-Device and the resulting (partial) loss of the functional safety application.

Validate the overall safety-related function with regard to the downtime of the F-Device during address assignment.

Make sure that all F-Hosts involved have a unique F-Source address.

Prior to commissioning the safety application, make certain that suitable organizational measures (according to applicable sector standards) have been taken to avoid hazardous situations if the safety-related logic application operates in an unintended or incorrect way.