Redundancy-specific system variables
Available for RFC 4072R from 2022.0 LTS
In addition to the general PLCnext Technology system variables, the following system variables are available for operating a redundant system of controllers.
Information on the redundant control system
Redundancy role
The LOCAL_RDNCY_INFO system variable is organized as a data structure. The LOCAL_RDNCY_INFO system variable can be used to retrieve various information on the redundant control system.
| System variable | Type | Description |
| LOCAL_RDNCY_INFO | LOCAL_RDNCY_INFO_TYPE | Data structure |
| └ RDNCY_IS_FIRST | BOOL | If true then redundancy type of the controller isFirst. |
| └ RDNCY_IS_SECOND | BOOL | If true then redundancy type of the controller isSecond. |
| └ RDNCY_IS_PRIMARY | BOOL | If true then redundancy role of the controller is PRIMARY. |
| └ RDNCY_IS_BACKUP | BOOL | If true then redundancy role of the controller is BACKUP. |
| └ RDNCY_BASICSYNC_OK | BOOL | If true then the redundant control system is in the Basic Sync state. |
| └ RDNCY_FOLLOWUPSYNC_OK | BOOL | If true then the redundant control system is in the FollowUp Sync state. |
| └ RDNCY_HSBY | BOOL | If true then the redundant control system is in the HotStandBy state. |
| └ RDNCY_ERROR | WORD | Digit of the last diagnosed error in the redundant control system. For details, see the Redundancy error codes |
| └ RDNCY_NUMBER_OF_SWITCH_OVER | INT | Number of redundancy role switch-overs since the last restart of the redundant control system. |
| └ RDNCY_LAST_SWITCH_OVER_REASON | INT | Cause for the latest redundancy role switch-over, shown as a digit. See next table for detailed descriptions. |
| └ RDNCY_SYNC_LINK_STATE | INT | Status of the physical connection at the SYNC interface: 1: Physical connection available 2: No physical connection available |
| └ RDNCY_CURRENT_SYNC_PORT | INT | Interface that is used for synchronization. Values: 1: LAN1 2: SYNC interface |
Causes for switch-over
The PRIMARY or BACKUP redundancy role of the controllers determines which of the two controllers manages the process. The most recent cause for a switch-over is indicated in PLCnext Engineer as a digit in the RDNCY_LAST_SWITCH_OVER_REASON system variable.
In addition, the most recent cause for a switch-over is displayed in PLCnext Engineer in the Cockpit → Redundancy Status → Switch Over Reason.
| Digit | Displayed in PLCnext Engineer | Description |
| 0 | None |
No switch-over of the redundancy role since the last time the PRIMARY controller was restarted. |
| 1 | FirmwareService |
The redundancy role was changed by the user. |
| 2 | RuntimeException |
A runtime error occurred on the PRIMARY controller. |
| 3 | LinkDownPnLan |
The physical network connection to Ethernet interface LAN1 was disconnected (LNK LED: off). |
| 4 | AllArsLost |
The PROFINET controller has lost the connection to all PROFINET devices via Ethernet interface LAN1. |
| 5 | ArLost |
The PRIMARY controller has lost the connection to at least one PROFINET device. |
| 6 | SystemShutdown |
The firmware of the PRIMARY controller was stopped by the user. |
| 7 | SystemTerminate |
The firmware of the PRIMARY controller was stopped due to an operating system exception that occurred. |
| 8 | PowerDown |
The PRIMARY controller was disconnected from the power supply. |
| 9 | SyncLinkTimeout |
A timeout occurred on the SYNC interface and on Ethernet interface LAN1. |
| 10 | InternalError |
An internal error occurred. |
Power supply
Available from firmware 2023.0 LTS with RFC 4072R only
The RFC 4072R as a dedicated redundancy controller must be set up with redundant power supplies. Therefore, the RFC 4072R is equipped with two power connectors, X1 and X2.
The POWER_SUPPLY and REMOTE_POWER_SUPPLY data structures provide boolean elements for each connector to indicate at which connector voltage is supplied to the RFC 4072R device and its companion in a redundant control system.
| System variable | Type | Description |
| POWER_SUPPLY | POWER_SUPPLY_TYPE | Data structure |
| └ X1 | BOOL | If true then voltage is supplied at that connector. |
| └ X2 | BOOL | If true then voltage is supplied at that connector. |
| REMOTE_POWER_SUPPLY | POWER_SUPPLY_TYPE | Data structure |
| └ X1 | BOOL | If true then voltage is supplied at that connector. |
| └ X2 | BOOL | If true then voltage is supplied at that connector. |
In addition, the RSC DeviceStatusService Status.PowerSupply.X1 and Status.PowerSupply.X2 can be used to query whether a device is supplied with power at the X1 and the X2 connector.
PROFINET system variables
PROFINET controller system variables
The PROFINET controller system variables can be used to retrieve various information on the integrated PROFINET controller functionality. All PROFINET controller system variables are available, except for the PNIO_FORCE_PRIMARY. No PROFINET device system variables are available.
PROFINET system variables on the remote controller
The REMOTE_PROFINET_INFO system variable is organized as a data structure. The REMOTE_PROFINET_INFO system variable can be used to retrieve various information on the integrated PROFINET controller functionality of the remote controller.
Note: The content of this system variable is only valid if the value of the variable LOCAL_RDNCY_INFO.RDNCY_SYNC_LINK_STATE is 1.
| System variable | Type | Description |
| REMOTE_PROFINET_INFO | REMOTE_PROFINET_INFO_TYPE | Data structure |
| └ PNIO_SYSTEM_SF | BOOL | Diagnostic alarm on a configured PROFINET device At least one PROFINET device is indicating a system error (diagnostic alarm or maintenance alarm). The error priority can be determined from the PNIO_DIAG_AVAILABLE, PNIO_MAINTENANCE_DEMANDED, and PNIO_MAINTENANCE_REQUIRED variables. |
| └ PNIO_MAINTENANCE_DEMANDED | BOOL | Maintenance demand At least one PROFINET device is indicating the maintenance demand alarm (high-priority maintenance alarm) with an active connection. The PROFINET device can be identified using the RALRM diagnostic block. |
| └ PNIO_MAINTENANCE_REQUIRED | BOOL | Maintenance required At least one PROFINET device is indicating the maintenance requirement alarm (low-priority maintenance alarm) with an active connection. The PROFINET device can be identified using the RALRM diagnostic block. |
| └ PNIO_CONFIG_STATUS | WORD | Configuration status of the PROFINET controller |
| └ PNIO_CONFIG_STATUS_ACTIVE | BOOL | This variable is set if the desired configuration for the PROFINET controller has been loaded. In this state, the PROFINET controller attempts to cyclically establish a connection to all devices in the desired configuration. |
| └ PNIO_CONFIG_STATUS_READY | BOOL | This variable is set if the PROFINET controller has been initialized correctly. No desired configuration has been loaded by PLCnext Engineer yet. |
| └ PNIO_CONFIG_STATUS_CFG_FAULT | BOOL | The desired PROFINET controller configuration has not been applied due to a serious error. In this case, please contact Phoenix Contact. |
| └ PNIO_FORCE_FAILSAFE | BOOL | All PROFINET devices are prompted to set their configured substitute values. If required the system variable can be written/set from the program. |
System time
System time on the active controller
see System variables - System time
System time on the remote controller
The REMOTE_DATE_TIME system variable is a system variable organized as a data structure. The REMOTE_DATE_TIME system variable can be used to retrieve information on the system time of the remote controller's internal real time clock (in short, RTC).
Note: The content of this system variable is only valid if the value of the variable LOCAL_RDNCY_INFO.RDNCY_SYNC_LINK_STATE is 1.
| System variable | Type | Description |
| REMOTE_DATE_TIME | RTC_TYPE | Data structure |
| └ HOURS | USINT | System time (hours) |
| └ MINUTES | USINT | System time (minutes) |
| └ SECONDS | USINT | System time (seconds) |
| └ DAY | USINT | System time (day) |
| └ MONTH | USINT | System time (month) |
| └ YEAR | UINT | System time (year) |
Device state
Device state on the active controller
see System variables - Device state
Device state on the remote controller
The REMOTE_DEVICE_STATE system variable is a system variable organized as a data structure. The REMOTE_DEVICE_STATE system variable can be used to retrieve various information on the device status of the remote controller.
Note: The content of this system variable is only valid if the value of the variable LOCAL_RDNCY_INFO.RDNCY_SYNC_LINK_STATE is 1.
| System variable | Type | Description |
| REMOTE_DEVICE_STATE | DEVICE_STATE_4xxx_TYPE | Data structure |
| └ BOARD_TEMPERATURE | SINT | Board temperature (in °C) |
| └ FAN_FAIL | BOOL |
The fan is defective.
Device defect due to overheating Immediately replace the fan when the defect occurs. |
| └ RAMDISK_USAGE | USINT | Memory used on the RAM disk |
| └ CPU_LOAD_ALL_CORES | USINT | Average current utilization of all processor cores (in %) |
| └ CPU_LOAD_PER_CORE | CPU_LOAD_PER_CORE_ARRAY | Information on the utilization per processor core |
| └ [1] | USINT | Current utilization of processor core 1 (in %) |
| └ [2] | USINT | Current utilization of processor core 2 (in %) |
Fan state
Fan state on the active controller
see System variables - Fan state
Fan state on the remote controller
The REMOTE_FAN_STATE system variable is a system variable organized as a data structure. The REMOTE_FAN_STATE system variable can be used to retrieve maintenance or failure information on the optional fan module of the remote controller.
Note: The content of this system variable is only valid if the value of the variable LOCAL_RDNCY_INFO.RDNCY_SYNC_LINK_STATE is 1.
| System variable | Type | Description |
| REMOTE_FAN_STATE | FAN_INFO | Data structure |
| └ FAN_MAINTENANCE | BOOL | Fan maintenance is required |
| └ FAN_DEFECT | BOOL |
The fan is defective.
Device defect due to overheating Immediately replace the fan when the defect occurs. |
User partition
User partition system variables on the active controller
see System variables - User partition
User partition system variables on the remote controller
The REMOTE_USER_PARTITION system variable is organized as data structure. The REMOTE_USER_PARTITION system variable can be used to retrieve various information and memory statistics about the user partition (overlay file system) of the remote controller. The partition is located on the external SD card of the remote controller. This memory is organized in blocks. A block has a constant, fixed size, and a file always occupies one or more blocks.
A certain number of blocks is reserved in the Linux system for the root user. Those reserved blocks are only available for the root user and ensure that the root user is able to act even if the memory is occupied (e.g. for log output).
Note: The content of this system variable is only valid if the value of the variable LOCAL_RDNCY_INFO.RDNCY_SYNC_LINK_STATE is 1.
| System variable | Type | Description |
| REMOTE_USER_PARTITION | PARTITION_INFO | Data structure |
| └ MEM_TOTAL | ULINT | Total memory of the partition in bytes (including reserved blocks) |
| └ MEM_FREE | ULINT | Free, available memory in bytes (without reserved blocks) |
| └ MEM_USED | ULINT | Occupied memory in bytes (including reserved blocks) |
| └ MEM_USAGE | USINT | Used memory in % (without reserved blocks) |