INSTALLATION AND OPERATING INSTRUCTIONS
Troubleshooting
SKF Multilog On-line System IMx-16Plus
User Manual
Revision Letter A
47 (66)
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 (with 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
In troubleshooting connections to Monitor (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 (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.
