43
When an unusual operating condition is detected by the AC drive control diagnostics, the drive initiates a notification
visible, for example, on the keypad. The keypad will show the ordinal number of the fault, the fault code and a short
fault description.
The fault can be reset with the Reset button on the control keypad or via the I/O terminal. The faults are stored in the
Fault history menu which can be browsed. The different fault codes you will find in the table below. This fault table
presents only the faults related to the fieldbus in use.
NOTE!
When contacting distributor or factory because of a fault condition, always write down all texts and codes on the
keypad display and send a description of the problem together with the Drive Info File to your local support.
When none of the devices on the RS-485 bus is sending data, all devices are in idle status. This being the case, the bus
voltage is in indefinate state, usually near 0 V due to the termination resistors. This may cause problems in character
reception because the single characters in serial communication begin with start bit referring to bus status ‘0’ with
voltage of less than -200mV whereas the bus status ‘1’ corresponds to bus voltage of more than +200mV. The RS-
485 standard considers the voltage interval -200mV...+200mV as undefined state. Bus biasing is therefore needed to
maintain the voltage in status ‘1’ (above +200mV) also between the messages.
To bias the bus you will have to add a separate active termination resistor specifically designed for the RS-485 bus (e.g.
Siemens active RS 485 terminating element (6ES7972-0DA00-0AA0)).
Table 48. Typical fault conditions
7.1 Typical Fault Conditions
7.2 RS - 485 Bus Biasing
7. Fault Tracing
Fault Condition
Possible Cause
Remedy
Termination
resistor
Missing or excessive termination resistor.
Install termination resistors at both ends of the
fieldbus line.
Cabling
• Supply or motor cables are located
too close to the fieldbus cable
• Wrong type of fieldbus cable
• Too long cabling
Grounding
Inadequate grounding.
Ensure grounding in all points on the net
Connections
Faulty connections.
• Excessive stripping of cables
• Conductors in wrong terminals
• Too loose connections of conductors
Parameter
• Faulty address
• Overlapping slave addresses
• Wrong baud rate
• Wrong control place selected
Summary of Contents for Praxi 100
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