Rockwell Automation 57C423 Common Memory Module - Manual (Page 22)

5Ć2
empty or contain a Processor module. If this is not the
case, multiple modules will respond to references.
If the module is not in slot 0, i.e., it is serving as data
storage, verify that the definition statements in the
configuration are associated with the correct slots.
Step 2. Verify that the variables are being referenced correctly.
Verify that all tasks that reference variables on this module
declare them COMMON. Only one task should be writing
to any one variable.
Step 3. Verify that the module can be accessed.
Connect the personal computer to the system and run the
Programming Executive Software.
Stop all programs that may be running.
If the module is in slot 0, use the VARIABLE MONITOR to
read and write to the variable by name. If the variable
cannot be accessed correctly, proceed to step 4.
If the module is in any even slot other than 0, use the I/O
MONITOR to read and write to the desired register. If the
register cannot be accessed correctly, proceed to step 4.
Step 4. Verify that the hardware is working correctly.
Systematically swap out the Common Memory module
and the Processor module(s). Make certain power is off
before removing any module from the rack. After each
swap, if the problem is not corrected, replace the original
item before going on to the next item. If the problem
persists, take all of the modules except one Processor
module and the Common Memory module out of the
backplane. If the problem is now corrected, one of the
other modules in the rack is malfunctioning. Reconnect
the other modules one at a time until the problem
reappears. If none of these tests reveals the problem,
replace the rack/backplane.
5.4 Bus Error
Problem: A 31" or 51" through 58" appears on the Processor
module's LED. This error message indicates that there was a bus
error when the system attempted to access the module. The possible
causes of this error are a missing module, a module in the wrong
slot, or a malfunctioning module. Use the following procedure to
isolate a bus error:
Step 1. Verify that the Common Memory module is in the correct
slot.
If the module is in slot 0, proceed to step 4. If the module
is in any other even slot, proceed to step 2.
Step 2. Verify that the module can be accessed.
Connect the personal computer to the system and run the
Programming Executive Software.
Stop all programs that may be running.
The cause of a 31" error message is most likely an error
in an address calculation performed by an application