Need explantion of Bus-timeout light on AC460 Advant controllers
- Timeout light on AC460's
This indicator was designed to indicate the occurence of an internal bus-error when the CPU in the controller attempted to access some piece of memory (or MIB module (such as an MVI board). In other words, there was a failure of the CPU to access a memory address.
The problem with this light is that it is normal during controller operation for these types of errors to occur.
- The controller software is continually 'polling' empty module slots to determine when a module is inserted (to support 'live' insertion capability). Each of these accesses would cause a bus-error (and potentially turn on the light). When controller-pairs become redundant there are some accesses which force bus-errors in order to test the communication between backup and primary.
There is no software control over this light. It is turned 'on' by hardware detection of a bus-error. There is no direct way for software to turn it off either. It can be turned off in software, but only at the expense of detrimentally affecting other controller hardware.
- Don't understand the meaning of an indicator