Rockwell Automation 57C442 Data Highway Plus Interface Module - Manual (Page 40)

5-2
5.3.2 Remote Station and Link Failure
When the Data Highway Plus Interface module is not initiating
messages, but is simply responding to unsolicited commands from
remote stations, a failure in the remote stations cannot be detected by
the module itself except by monitoring the active station list
(registers 34-37).
When the module is initiating messages, a link failure is indicated by a
Response Timeout error.
5.4 Bus Error
Problem: Error codes “31” appears on a Processor module’s LED
display. This error indicates the system has a problem accessing a
module in the rack though the backplane bus. A bus error may be
caused by removal of a module, a module failure, or a rack backplane
failure.
Use the following procedure to isolate a bus error:
Step 1. Verify that all modules are in the correct slot.
Verify that the slot number being referenced in the application tasks
agrees with the slot number defined during configuration.
Step 2. Verify the station address is correct.
The thumbwheel switches used to set the station address can be
changed while the module is on-line without having any effect on the
system. On the next power up, if the thumbwheel switches define a
station that is valid, the Processor will accept it as a valid station.
Step 3. Verify that the application software is correct.
Verify that the application software is not attempting to write to READ
ONLY registers on the module.
Step 4. Verify that the hardware is working correctly.
Make certain that power is off before removing any module from the
rack. Systematically replace the Data Highway Plus Interface module,
the Processor module(s), and the rack/backplane, one at a time, with a
corresponding module or assembly known to be operating correctly.
After replacing each module or assembly, if the problem is not
corrected, replace the original item before going on to the next item.
!
ATTENTION: This equipment is at line voltage when AC
power is connected. Disconnect and lockout all ungrounded
conductors of the AC power line. Failure to observe this
precaution could result in severe bodily injury or loss of life.