5.1.4
Data bus failures
Functioning of data bus is signalled by flashing of pair of yellow ”TXR” and ”RXR” LEDs, that signal transmitting
of a message into the bus (flashing of ”TXR” LED) and receiving of a message from the bus (flashing of ”RXR”
LED).
Data bus failures manifest themselves by full or partial malfunctioning of the bus communication. Module with
inoperative data bus communicates through its configuration port, responds to configuration commands, but the
messages from some of the connected meters (or from all of them) do not come to the radio network (or vice versa
- messages from the radio network don’t come to the devices on the bus.). In some cases the malfunction of the bus
is partial - interruptions are either random in time or their affect is limited to only some of the connected devices
(meters, sensors).
Data bus failures and breakdowns can be caused by following reasons:
•
incorrect setting of data bus parameters as decribed inparagraph
, or discrepancy between bus parameters
of the module and connected device;
•
mechanical damage of the bus cable;
•
fault of module’s link amplifier;
•
worsening of the bus transmission capacity as a result of some changes or modifications of the bus (...a new
device connected to bus, order alteration, wiring replacement, terminator connection/disconnection...);
•
disturbance of the electrical signal within the bus by induction of the interfering signal into the bus, or troubles
caused by differences of electrical potential among devices connected to the bus.
Recommendation:
Troubles with bus transmission capacity as described in the last two items generally occur
especially if there is a bus with lengthy wiring and with high number of connected devices. Troubleshooting of the
bus failures can be quite complicated and requires a specific knowledge and experiences. It is recommended to entrust
the task to the specialist with experiences with given type of bus.
If there is a suspicion that the operational troubles with data collection from the remote bus could be caused by fail-
ure of data bus itself, first of all check correctness of data collection system settings, especially correct identification
(addressing) of individual devices within central system (master) database. If the correctness of the identification
is positively checked, proceed with troubleshooting of the data bus communication malfunctioning in following steps:
•
visually check whether the bus cable from the given meter/sensor is attached correctly to the module and test
its functionality by ohmmeter. If the inspection of the cable shows any signs of its damage (or it is evidently
inoperative), repair or replace the cable immediately;
•
if the bus wiring is undamaged and messages from other devices on the same bus came to the central system
correctly, check consistency of setting of bus parametres within the module configuration and within the
connected meter/sensor as described in the paragraph
”
Setting of parameters of the M-Bus bus”
•
if the bus is physically functional and its configuration is correct and consistent with setting of connected
devices, but the communication through the bus is still non-functional, the WM868-MS-LP-H module is
probably defective and it is necessary to make its replacement as described in the paragraph
•
if the bus communication will not work properly even after replacement of the module, the bus is physically
apparently functional, configuration of the module is correct, addressing is in harmony with setting of bus
”
Master”, but the messages still dont pass through the bus, the bus is probably not working correctly on
the data level. In this case try to make some changes in the bus setting on the
”
Master” side (different
speed, different Inter-Byte timeout...) that is possible to make and could have some influence on the bus
communication. In this case it is recommended to ask for advice/support some person with broad experiences
in bus communication or module producer.
5.2
Troubleshooting procedure
To identify a reason of device failure or any anomaly in its operation follow this procedure:
1. No data are available from any remote segment of WACO virtual bus. In this case it is recommended to check
functionality of the module subsystems in following order:
•
check functionality of power supplying as described in the paragraph
”
Power supplying failures”
•
check functionality of the system as described in the paragraph
”
System failures”
•
check bus functionality as described in the paragraph
”
Data bus failures”
•
check transmitting and receiving functionalities as described in the paragraph
”
Transmitter and
receiver failures”
WM868-MS-LP-H
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