INSTALLATION AND OPERATING INSTRUCTIONS
Troubleshooting
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SKF Multilog On-line System IMx-8/IMx-8Plus
User Manual
Revision E
communications test will be successful. Pay attention also to bus termination and
grounding, as described in section
When using the interface, the connection will be between a single master and one
–
or sometimes more
–
slave devices and each slave must have a unique address in
the range 1 to 247. The master device initiates all communications and the slave
device only ever responds, if asked to send a reply. Incorrect addressing, a mismatch
between the address at which the master understands the slave resides and that
actual address, will result in unanswered messages.
The Modbus RTU protocol exchanges binary data across the bus. Detection of
message start and message end rely on certain bit state combinations and inter-
message minimum pauses during which there is no communications traffic. For each
device on the bus to correctly interpret these from the electrical patterns on the bus
requires an equal understanding of the bit allocations and the bit rate or baud rate,
being used. Commonly an arrangement known as 8-N-1 (eight data bits, no parity bit
and one stop bit) transmitted at 9 600 or 19 200 bits per second are used. If devices
are differently set, by configuration or otherwise, communications will fail.
For further information on RS485 and Modbus RTU,
2.9.6 Connections to Monitor
The status of the connection to the @ptitude Observer Monitor server (connected or
not) is reflected by bit 14 of the Modbus register 30029 (refer to the Modbus for SKF
IMx and @ptitude Observer user manual, part number 15V-090-00051-100). This
can be especially useful to verify current connection status in any applications, such
as mobile or marine, where a continuously available connection is not expected.
In troubleshooting connections to Monitor, especially a loss of connection rather than
initial commissioning, consider first the following aspects:
•
That the PC hosting the Monitor service is currently operational
•
It can access and write to the database
•
If the status of the Monitor software is uncertain, try restarting the PC
•
Check for issues on the network infrastructure, from IMx to that PC
•
Any recent IT changes that may have impacted the system such as
modifications to a firewall, security, etc.
In a multi-IMx system indications of where the fault may lie can be inferred from
knowing how many and which IMx have problems connecting.
