bonitron M3452, Customer Reference Manual

Page: 37 / 80

User’s Manual
37
4.2.4.4.5. PROFIBUS T
ROUBLESHOOTING
The module routinely performs internal diagnostics following power-
up or reset.
During this period, the green “Run” LED will flash for a
moment.
If the diagnostics complete OK, the “Run” LED will stop
flashing after a few seconds and remain ON. This indicates the unit
is operating normally.
Once
the unit has passed through the initialization,
parameterization, and configuration states, and is in data exchange
mode, the yellow BUS LED will be ON. If the BUS LED is OFF and
the unit is connected to the network, then this is indicative of an
initialization problem.
Tips for Building a PROFIBUS Network
•
Follow the PROFIBUS installation guidelines.
•
Use the recommended cable and connectors of the standard.
•
Verify that none of the wires are broken or shorted.
•
Don’t mix the A & B lines. Use green wire for A and red wire
for B.
•
Do not exceed the recommended segment length for the baud
rate.
•
Make sure that there are no more than 32 RS-485 devices per
segment (including the master device and the repeater).
•
Check for proper termination of all copper-wire network
segments (an RS-485 segment must have a termination
resistor at both ends of the segment only).
•
All activated terminations must be powered all the time. If this
is not possible, then consider using an active-termination box.
•
Check whether the station address is set to the correct value.
•
If your network connects between buildings or runs through
hazardous environments, consider the use of fiber-optics.
•
Avoid drop lines and keep their length within the specified
maximum.
For T-drops, consider using repeaters and active-bus terminations.
Four most common PROFIBUS problems
1. Incorrect slave address set at the slave.
2. PROFIBUS connector between the master and slave has its
termination switch turned ON.
3. Incorrect module configuration sent to slave.
4. Configuration is based on outdated GSD file information.