Chapter 7: Service and troubleshooting
EST3X Technical Reference Manual 217
subchains created during the mapping process create a loop map. If a loop fails
to map properly, investigate the devices making up chains and subchains to find
the reason. Click the Device Chains tab to display a chain generated during the
failed mapping process. Press F1 to open the Help topic that provides
instructions and descriptions for the information provided.
Examine the chain and look for gaps within the address or serial number lists in a
chain or subchain.
• Gaps in the list indicate areas that were not successfully mapped. A gap
within the chain does not mean that the missing device has a problem; it
means that the device was not successfully mapped.
• Compare the Chain Response and Device Response lists. All the devices on
the Device Response list should also appear on the Chain Response list.
• Look for duplicate addresses or serial numbers on the same list.
Failure of a device to successfully map may be the result of a problem with
another device, or wiring in a chain or subchain not directly connected to the
unmapped device. Although the missing or duplicate devices are not always the
cause of map failure, these devices should be examined for defects and wiring
errors, and for duplicate entries in the 3-SDU.
Message counters diagnostics
During normal operation, the Signature loop controller module issues
communication messages to the Signature devices on its loop. Message
counters indicate how many times a communication message has been issued
and the number of successful return messages. During normal operation, the
percentage of messages received correctly should exceed 99%. Intermittent
device or wiring problems are indicated by a low successful message rate.
Click the Message Counters tab to check the loop controller’s message error
rate. Press F1 to open the Help topic that provides instructions and descriptions
for the information provided.
Preventive measures can be taken by establishing a baseline of successful
messages over a period time for each loop. From the base line information, any
changes from the norm can be quickly identified and corrected before a
communication problem develops.
Device troubles diagnostics
Each Signature device is equipped with a 32-bit trouble register. Should a
device’s trouble bit be set at any time in the device’s history, the device and the
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