Hot Standby DDT Data Structure

Introduction

The T_M_ECPU_HSBY DDT is the exclusive interface between the M580 Hot Standby system and the application running in a BMEH58•040 or BMEH58•040S controller. The DDT instance should appear as: ECPU_HSBY_1.

NOTICE

RISK OF UNINTENDED OPERATION

Review and manage the T_M_ECPU_HSBY DDT for proper operation of the system.

Failure to follow these instructions can result in equipment damage.

The T_M_ECPU_HSBY DDT presents three distinct sections:

LOCAL_HSBY_STS: Provides information about the local controller. Data is both auto-generated by the Hot Standby system, and provided by the application. This data is exchanged with the remote controller.
REMOTE_HSBY_STS: Provides information about the remote controller, and contains the image of the last received exchange from the counterpart controller. The validity of this information is represented by the REMOTE_STS_VALID flag in the common part of this DDT.

NOTE: The structure of both the LOCAL_HSBY_STS and Remote_HSBY_STS sections are determined by the HSBY_STS_T data type, and are therefore identical. Each is used to describe data relating to one of the two Hot Standby controllers.
A common part of the DDT: Consists of several objects, including status data, system control objects, and command objects:
- Status data is provided by the Hot Standby system as a result of diagnostic checking.
- System control objects enable you to define and control system behavior.
- Command data objects include executable commands you can use to modify the system state.

Local Controller versus Remote Controller

The T_M_ECPU_HSBY DDT employs the terms local and remote:

Local refers to the Hot Standby controller to which your PC is connected.
Remote refers to the other Hot Standby controller.

Data Boundary Alignment

M580 BMEH58•040 and BMEH58•040S controllers feature a 32-bit data design. For this reason, stored data objects are placed on a four-byte boundary.

T_M_ECPU_HSBY DDT

CAUTION

RISK OF UNINTENDED OPERATION

Before you execute a swap command (either by application logic or in the Control Expert GUI) confirm that the standby controller is ready to assume the primary role by verifying that the value of its REMOTE_HSBY_STS.EIO_ERROR bit is 0.

Failure to follow these instructions can result in injury or equipment damage.

The T_M_ECPU_HSBY DDT consists of these objects:

Element	Type	Description	Written by
REMOTE_STS_VALID	BOOL	True: Both HSBY_LINK_ERROR and HSBY_SUPPLEMENTARY_LINK_ERROR are set to 0. False (default): Both HSBY_LINK_ERROR and HSBY_SUPPLEMENTARY_LINK_ERROR are set to 1.	System
APP_MISMATCH	BOOL	The original application in the two controllers is different. (Default = false)	System
LOGIC_MISMATCH_ALLOWED	BOOL	True: The standby remains standby in case of logic mismatch. False (default): The standby goes into wait state in case of logic mismatch.	Application
LOGIC_MISMATCH	BOOL	Different revisions of the same application exist in the two controllers. (Default = false)	System
SFC_MISMATCH	BOOL	True: The applications in the primary controller and the standby controller are different in at least one SFC section. In the event of a switchover, the graphs that are different are reset to their initial state. False (default): All SFC sections are identical.	System
OFFLINE_BUILD_MISMATCH	BOOL	The two controllers are running different revisions of the same application.In this condition: A data exchange between the two controllers may not be possible. A swap or switchover may not be transparent. Neither controller can be standby (Default = false)	System
APP_BUILDCHANGE_DIFF	UINT	The number of build change differences between the applications in the primary controller versus the standby controller. Evaluated by the primary.	System
MAX_APP_BUILDCHANGE_DIFF	UINT	Maximum number of build change differences permitted by the Hot Standby system, from 0...50 (default = 20). Set in the Hot Standby tab as Number of modifications .	Application
FW_MISMATCH_ALLOWED	BOOL	Allows mismatched firmware between primary and standby controllers: True: the standby remains standby in case of FW mismatch. False (default): the standby goes into wait state in case of FW mismatch. (Default = false)	Application
FW_MISMATCH	BOOL	The OS are different in the two controllers. (Default = false)	System
DATA_LAYOUT_MISMATCH	BOOL	The Data layout are different on the two controllers. The data transfer is partially performed. (Default = false)	System
DATA_DISCARDED	UINT	Number of KB sent by the primary and discarded by the standby (rounded up to the next KB). Represents data for variables added to primary, but not to standby. (Default = 0)	System
DATA_NOT_UPDATED	UINT	Number of KB not updated by the standby (rounded up to the next KB). Represents variables deleted from the primary that remain in the standby. (Default = 0)	System
BACKUP_APP_MISMATCH	BOOL	False (default): The backup application In the 2 Hot Standby controllers are equal. NOTE: The backup application resides in flash memory or on the SD memory card of the controller. It is created either by the PLC > Project Backup... > Backup Save command, or by setting the %S66 system bit (Application Backup) to 1. True: All other cases.	System
PLCA_ONLINE	BOOL	Controller A is configured to enter the primary or standby state. (Default = true) NOTE: Executable only on controller A.	Configuration
PLCB_ONLINE	BOOL	Controller B is configured to enter the primary or standby state. (Default = true) NOTE: Executable only on controller B.	Configuration
CMD_SWAP	BOOL	Set to 1 by program logic or animation table to initiate a switchover. The primary goes into wait, then the standby goes primary, finally the wait goes standby. The command is ignored if there is no standby. NOTE: Executable on both primary and standby. Reset to 0 (default) by the system on switchover completion or if there is no standby. NOTE: This command is designed to be used by the application in response to detected errors. It is not intended to be used for periodic switchovers. If the application has to switchover periodically, the period between switchovers must not be less than 120 seconds.	Application / System
CMD_APP_TRANSFER	BOOL	Set to 1 by program logic or animation table to start an application transfer from the primary to the standby. Executable only on the primary. NOTE: The application transferred is the backup application, stored in flash memory or on the SD card. If the application running does not match the backup application, perform an application backup (PLC > Project Backup... > Backup Save or set the %S66 system bit to 1) before performing the transfer. Reset to 0 (default) by the system on transfer completion.	Application / System
CMD_RUN_AFTER_TRANSFER	BOOL[0...2]	Set to 1 by program logic or animation table to automatically start in Run after a transfer. NOTE: Executable only on the primary. Reset to 0 (default) by the system after transfer completion and: remote controller is in Run Controller is not primary by animation table or logic command	Application / System
CMD_RUN_REMOTE	BOOL	Set to 1 by program logic or animation table to run the remote controller. This command is ignored if the CMD_STOP_REMOTE is true. NOTE: Executable only on the primary. Reset to 0 (default) by the system when the remote controller enters standby or wait state.	Application / System
CMD_STOP_REMOTE	BOOL	Set to 1 by program logic or animation table to stop the remote controller. NOTE: Executable on the primary, the standby, or a stopped controller. Reset to 0 (default) by the application to end the stop command.	Application
CMD_COMPARE_INITIAL_VALUE	BOOL	Set to 1 by program logic or animation table to begin a comparison of the initial values of variables exchanged by the two Hot Standby controllers. NOTE: Executable on both primary and standby only in Run mode. Reset to 0 (default) by the system when the comparison is complete, or if the comparison is not possible.	Application / System
INITIAL_VALUE_MISMATCH	BOOL	True: if the initial values for exchanged variables are different or if the comparison is not possible. False (false): if the initial values for exchanged variables are identical.	System
MAST_SYNCHRONIZED ⁽¹⁾	BOOL	True: if the exchanged data from the previous MAST cycle was received by the standby. False (default): if the exchanged data from at least the previous MAST cycle was not received by the standby. NOTE: Closely monitor the MAST_SYNCHRONIZED and FAST_SYNCHRONIZED variables related to the MAST and FAST tasks as indicated at the end of this table.	System
FAST_SYNCHRONIZED ⁽¹⁾	BOOL	True: if the exchanged data from the previous FAST cycle was received by the standby. False (default): if the exchanged data from at least the previous FAST cycle was not received by the standby. NOTE: Closely monitor the MAST_SYNCHRONIZED and FAST_SYNCHRONIZED variables related to the MAST and FAST tasks as indicated at the end of this table.	System
SAFE_SYNCHRONIZED	BOOL	True: if the exchanged data from the last SAFE cycle was received by the standby. False (default): if, at least, the exchanged data from the last SAFE cycle was not received by the standby.	System
SAFETY_LOGIC_MISMATCH	BOOL	True: the SAFE logic part of the application is different in the two controllers. False (default): the SAFE logic part of the application is identical in the two controllers. NOTE: The content for this element is determined by comparing system word %SW169 for each controller.	–
LOCAL_HSBY_STS	T_M_ECPU_HSBY_STS	Hot Standby status for the local controller	(see below)
REMOTE_HSBY_STS	T_M_ECPU_HSBY_STS	Hot Standby status for the remote controller	(see below)
(1): Closely monitor the MAST_SYNCHRONIZED, FAST_SYNCHRONIZED, and SAFE_SYNCHRONIZED variables related to the MAST, FAST and SAFE tasks. If its value is zero (False), then the database exchanged between the primary and the standby controllers is not transmitted at each cycle. In this situation, change the configured period of this task with a higher value than its current execution time (for the MAST task: %SW0 > %SW30; for the FAST task %SW1 > %SW33; for the SAFE task %SW4 > %SW42. More details on %SW0 + %SW1 and %SW30 + %SW31 in EcoStruxure™ Control Expert, System Bits and Words, Reference Manual). Example of consequence: upon an Application Program Transfer (APT) command, the primary controller might not be able to transfer the program to the standby controller.

T_M_ECPU_HSBY_STS Data Type

The T_M_ECPU_HSBY_STS data type presents the following elements:

Element	Type	Description	Written by
HSBY_LINK_ERROR	BOOL	True: No connection on the Hot Standby link. False: The Hot Standby link is operational.	System
HSBY_SUPPLEMENTARY_LINK_ERROR	BOOL	True: No connection on the Ethernet RIO link. False: The Ethernet RIO link is operational.	System
WAIT	BOOL	True: The controller is in Run state but waiting to go primary or standby. False: The controller is in standby, primary or stop state.	System
RUN_PRIMARY	BOOL	True: The controller is in primary state. False: The controller is in standby, wait or stop state.	System
RUN_STANDBY	BOOL	True: The controller is in standby state. False: The controller is in primary, wait or stop state.	System
STOP	BOOL	True: The controller is in stop state. False: The controller is in primary, standby or wait state.	System
PLC_A	BOOL	True: the controller A/B/Clear switch is in “A” position. False: the controller switch is not in “A” position.	System
PLC_B	BOOL	True: the controller A/B/Clear switch is in “B” position. False: the controller switch is not in “B” position.	System
EIO_ERROR	BOOL	True: The controller does not detect any of the configured Ethernet RIO drops. False: The controller detects at least one configured Ethernet RIO drop. NOTE: This bit is always false when no drop is configured.	System
SD_CARD_PRESENT	BOOL	True: A valid SD card is inserted. False: No SD card, or an invalid SD card is inserted.	System
LOCAL_RACK_STS	BOOL]	True: The local rack configuration is OK. False: The local rack configuration is not OK (for example, modules missing or in incorrect slots, etc.)	Application
MAST_TASK_STATE	BYTE	State of the MAST task: 0: Not existent 1: Stop 2: Run 3: Breakpoint 4: Halt	System
FAST_TASK_STATE	BYTE	State of the FAST task: 0: Not existent 1: Stop 2: Run 3: Breakpoint 4: Halt	System
SAFE_TASK_STATE	BYTE	State of the SAFE task: 0: Not existent 1: Stop 2: Run 3: Breakpoint 4: Halt	System
REGISTER	WORD[0...63]	Unmanaged data added to the application via the Exchange on STBY attribute.	Application