Because RFL™ and Hubbell® have a policy of continuous product improvement, we reserve the right to change designs and specifications without notice.
8.2.3 T1 CARRIER-LEVEL ERRORS
A port may have errors even if the front panel Alert indicator is not on. For example, low-level bit
errors may be occurring, but at a level under the user set threshold. A detailed report regarding the
condition of a port may be viewed as described in paragraph 8.2.2.
Low-level errors may be caused by a bad transmit from the remote equipment, a poor link between
nodes (such as a weak or noisy signal), or a faulty receiver in the DACS module or CM4 modules.
These problems are evaluated similarly to the port problems discussed as gross errors above, but
require a more careful examination to evaluate performance.
No errors reported by the receiver on the port indicates that the data has passed between nodes without
errors. That is, the data was received by the M-DACS as it was transmitted by the connected
equipment. If the information in the data stream was corrupted prior to reaching the transmit circuits
of the other equipment, this cannot be detected by the M-DACS.
8.2.4 PAYLOAD (DS0) ERRORS
Occasionally errors may occur in the payload of a signal without any errors being reported on the T1
level. Given the very nature of the M-DACS this implies errors are suspected between two remote
pieces of equipment whose data passes through the DACS module. Therefore this type of error
necessarily includes numerous pieces of equipment and can have virtually limitless configuration
options.
Diagnosing payload problems becomes further complicated because of the different types of payload
data and how they can be traced and monitored. In general the first step is to confirm that the problem
lies within the DACS module or the CM4 and not elsewhere in the system.
1. When possible the signal being received by the M-DACS should be confirmed to be free of errors.
This can usually be performed by monitoring the port diagnostics counters using the IMUX 2000
NMS, under the DACS module (Port 1 to Port 8) Status screen, and under the CM4 D/I-A and D/I-
B Configuartion/Status screen.
2. After verifying the received data is correct, the transmit signal should be similarly verified by
performing item number 1 at the remote end.
3. If the problem is isolated to within the DACS module and/or the CM4s, the configuration should
be re-checked. For the DACS module, particular attention must be made to ensure that the
incoming DS0 is correctly mapped to the outgoing DS0. The signaling configuration must also be
verified. In a T1 system if a DS0 is configured for RBS when it is not supposed to be it will
corrupt the data. If is supposed to be configured for RBS and it is not, the signaling will not be
passed by the DACS module.
4. If the problem is confirmed to lie within the DACS module and/or the CM4s and that the
configuration is correct, the DACS module and/or the CM4s should be replaced.
M-DACS-T1 RFL Electronics Inc.
October 25, 2004 8-3 (973) 334-3100
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