Rockwell Automation T8310 Trusted Expander Processor - Manual (Page 21)

Trusted
TM
Module T8310
Issue 12 Dec 06 PD-T8310 21
4. Operation
4.1. Standby
Standby is the default mode of operation for the module, once internal supply levels are established. In
this mode the module may receive messages addressed to the module itself over the IMB or Expander
Bus. Response messages over the Expander Bus will only be transmitted following a transition to the
Active mode. The module does not provide the capability of passing messages to and from other
modules within the Expander Chassis in this mode.
4.2. Active
In the active mode, the module is responsible for the forwarding of messages from the Expander Bus
to the Expander Chassis IMB, and response messages from the Expander Chassis IMB to the
Expander Bus. The module also provides all of the functions available within the Standby mode of
operation.
4.3. Expander Processor Module Active/standby Control
The TMR Expander Processor Modules transition between active and standby (and vice-versa) is
controlled locally by negotiation between two TMR Expander Processor Modules. Interlocks are
incorporated within the TMR Expander Processor module to ensure that both modules within an
active/standby configuration can not assume active mode operation.
Where both modules are healthy, the active operation defaults to the left-most module.