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Topic: P183

Hot Swap Information

Description

The term Hot Swap refers to the process of replacing system Modules without shutting down the system. The main reason to use Hot Swapping is to change Modules without significant interruption of a system.

Hot Swapping Cautions: Hot Swapping, while convenient at times, requires understanding and knowledge of electrical and component function.  In order to make a system Hot Swappable, the ladder logic design must be made by a qualified programmer who understands how to allow Hot Swapping without harming the system.

Keep in mind that Hot Swapping is performed with a HOT (powered) system.  Therefore, EXTREME care MUST be taken to prevent damage to components, terminal blocks, or even personal injury due to a short circuit from the live terminal block.  ONLY QUALIFIED TECHNICIANS SHOULD PERFORM HOT SWAPS!

Hardware Configuration Settings

The following settings are made in the Hardware Configuration window for each module:

  1. Two possible settings for I/O Modules

Note: Automatic Module Verification (Electronic Keying) is in reference to the Module ID assigned to each module. When replacing system modules, the ID is verified to make sure it is the same as configured in the hardware configuration.

  1. Two possible settings for P3-RS/P3-RX/P2-RS/P1-RX (Remote Slave)

CAUTION: CPUs and local expansion modules are not hot-swappable. Removing a CPU or expansion module while the system is powered can result in irreparable damage to the module.


Allow program to run with this system disconnected (hot-swap)

The Allow program to run with this system disconnected (hot-swap) option will enable the " hot swap functionality for every unit in that group, base or system. This will allow the system to run a project without the configured I/O in place. To select this option, right click the desired Base or Group , or for System, left click on red " Allow program to run..." icon from the hardware configuration page as seen below.

SYSTEM

BASE

GROUP

Once selected, one of the following windows will appear asking the user to verify the selection.

For a quick reference for each module selected for Hot Swap, a corresponding red dot will appear above each module:

Note: If additional P3-RS/P3-RX/P2-RS/P1-RX or I/O modules are added to the system, the default setting will be the ‘Stop program when this base group is disconnected’ mode. To enable Hot Swap in these modules, you will need to select the Allow program to run with this base group disconnected (hot swap) option again or select the Allow program to run with this module disconnected option manually in each module.

I/O Modules

The I/O Modules settings tell the CPU how to respond to a mismatch between the hardware installed in that slot and the Hardware Configuration of the project in the CPU.  Mismatch situations may include:

  1. Stop program when this module is disconnected:Enabling causes the CPU to treat a hardware mismatch in that slot as a critical error.  The critical error will force the CPU to stop mode.  This is the default setting.
  2. Allow program to run with this module disconnected:Enabling causes the CPU to treat a hardware mismatch in that slot as a non-critical error.  Since the error is non-critical it will not force the CPU to Stop Mode and will do the following:

If installed in a remote base and that base’s master is configured for hot swap, these options will be greyed out. To require these modules for the CPU to run, the master must be configured to Stop program when this base group is disconnected

P3-RS/P3-RX Modules

P3-RS/RX/P2-RS/P1-RX modules are used to control Remote Base Groups.  The P3-RS/RX /P2-RS/P1-RX settings tell the CPU whether communications with that Base Group is required to allow run mode for the system.

Note: When using a P3-RS/RX/P2-RS/P1-RX Remote I/O module, the settings of I/O Modules in its Base Group are not overridden by those of the Remote I/O module. So regardless of the detection settings of the Remote I/O module, any module in that Base Group with Stop program when this module disconnected selected must be Seen by the CPU to allow run mode for the system.

If it is desirable to be able to power down (or lose communications with) a Remote Base Group without the CPU going to stop, select Allow program to run with this base group disconnected (hot swap) for the P3-RS/RX/P2-RS/P1-RX. Hot swap mode will be automatically applied to all modules in the selected base.

  1. Stop program when this base is disconnected: Enabling causes the CPU to treat the loss of communications with this Base Group as a critical error. The critical error will force the CPU to stop mode. This is the default setting.
  2. Allow program to run with this base group disconnected (hot swap): Enabling causes the CPU to treat the loss of communications with this Base Group as a non-critical error. Since the error is non-critical it will not force the CPU to stop mode. (All I/O Modules in the Base Groupmust have NV selected for loss of communications with the Base Group to be treated as non-critical error by the CPU.) In this case the CPU will do the following:

System Tags associated with Hot Swappable I/O

The following System Tags can be used in conjunction with your ladder program to build in notification of errors when a module is Hot Swapped without the system dropping from Run mode. The status of these System Tags identify the state of the configuration regardless of whether Stop program when this base is disconnected or Allow program to run with this base group disconnected (hot swap) is selected.

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