Executing Hot Standby Commands

Introduction

This topic shows you how to execute Hot Standby commands for an M580 BMEH58•040 or BMEH58•040S CPU. Hot Standby commands can be executed using:

The Control Expert graphical user interface CPU configuration screens, which include:
- The Task tab of the Animation window.
- The Hot Standby window.
The T_M_ECPU_HSBY and T_M_ECPU_HSBY_STS DDTs, which can be called using:
- Program logic.
- An Animation Table , where you can use the Force and Modification commands.

NOTE: The M580 Hot Standby system does not support the use of the Quantum Hot Standby elementary function blocks (EFBs), including: HSBY_RD, HSBY_ST, HSBY_WR and REV_XFER. Instead, these functions are directly managed by DDDT commands.

For information on how to operate the non-Hot Standby functions for the CPU, refer to the M580 Hardware Reference Manual.

Hot Standby Commands

CAUTION

RISK OF UNINTENDED OPERATION

Before executing a swap, either by application logic or in the Control Expert GUI, verify that the standby PAC is ready to assume the primary role.

Refer to the EcoStruxure™ Control Expert Program Languages and Structure Reference manual for more details on the %SW182-%SW183 and %SW176-%SW177 system words.

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

The M580 BMEH58•040 and BMEH58•040S CPUs support the following Hot Standby commands:

Command	Description	Executable on Primary or Standby	Supported by:
Command	Description	Executable on Primary or Standby	DDDT	GUI
CMD_APP_TRANSFER⁴	Transfers the application in the primary PAC to the standby PAC. NOTE: The backup application resides in flash memory or on the SD memory card of the PAC. It is created either by the PLC > Project Backkup... > Backup Save command, or by setting the %S66 system bit (Application Backup) to 1.	Both	X	X
CMD_COMPARE_INITIAL_VALUE	Compares the initial values of variables included in the Hot Standby data exchange.	Both (in RUN mode)	X	–
CMD_RUN_AFTER_TRANSFER	Places the primary PAC into RUN operating mode upon completion of transfer of application to standby PAC.	Primary only	X	–
CMD_RUN_REMOTE	Places the remote¹ PAC into RUN operating mode. Executable only on the primary CPU.	Primary only	X	X³
CMD_STOP_REMOTE	Places the remote¹ PAC into STOP operating mode.	Primary only	X	X³
CMD_SWAP	Manually performs a Hot Standby switchover. The primary goes into wait; the standby goes into primary; then the wait goes into standby. Executable on both the primary and the standby CPU. 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.	Both	X	X³
FW_MISMATCH_ALLOWED	When changes have been made to the firmware in the primary CPU, this command lets the standby CPU continue to operate as standby. If this command is set to 0, the standby goes into wait state.	Primary only	X	–
LOGIC_MISMATCH_ALLOWED⁴	When changes have been made to the application in the primary CPU (for example, as a a result of CCOTF changes), this command lets the standby CPU continue to operate as standby. If this command is set to 0, the standby goes into wait state.	Primary only	X	–
PLCA_ONLINE	Lets the CPU with its A/B/Clear rotary selector switch set to “A” serve as either primary or standby, depending on other operating conditions. If set to 0, PAC A goes into either wait or stop state.	PAC A only	X	X²
PLCB_ONLINE	Lets the CPU with its rotary switch set to “B” serve as either primary or standby, depending on other operating conditions. If set to 0, PAC B goes into either wait or stop state.	PAC B only	X	X²
X: Command is supported. –: Command is not supported. 1. Remote refers to the PAC to which your PC and Control Expert is not connected. 2. In the CPU configuration window Hot Standby tab. 3. In the CPU configuration window Animation > Task tab. 4. These commands can be executed only if the remote CPU is also the standby CPU.