Basic troubleshooting a SLF1 fault on Altivar71/61 drive.
All ATV61 ATV71
Fault condition drive will not run
A modbus communication fault indicates that the communication has worked properly between the drive and the master and, during the time set in [Modbus time out] (ttO) parameter, a loss of communication has been detected.
- Check the master state (RUN, stop…).
- Check if there is no network overload.
- Check the time out value (try to increase the value).
- Check the time between the sending of 2 Modbus requests (if the time is higher than the time out value, the drive can trip in fault).
- Use the Telemecanique cable with 2 pairs of shielded twisted conductors (catalog number: TSXCSA100, TSXCSA200 or TSXCSA500).
- Keep the Modbus cable away from the power cables (30 cm minimum).
- If it is necessary for the Modbus cable and the power cables to cross each other, be sure they cross at right angles
- A reflection in a transmission line is the result of an impedance discontinuity that a traveling wave sees as it propagates down the line. To minimize the reflections from the end of the RS485-cable, it is required to place a line termination near each of the 2 ends of the bus.
- Whenever possible, connect the cable shielding to the protective ground, e.g., to the ground of each device if this ground is connected to the protective ground.