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What causes Serial Link Fault (SLF) fault on an ATS22 Soft Starter?

Issue:
ATS22 soft starter SLF fault

Product Line:
ATS22 series soft starters

Environment:
All models, All serial numbers.

Cause:
SLF is an indication of Serial Link Fault. The starter has lost communication with the Modbus network.

Resolution:
Ensure that the Modbus network is connected properly to the starter and the network is passing traffic and has not faulted. Ensure that the modbus address on the starter is set correctly.
If no modbus network is being used with this starter, check parameter CtrL under the COP menu. For Local control via the terminals, this parameter should be set to LCL (factory default). For Modbus control it should be set to DBS. Note that you will not have access to the COP menu unless parameter LAC under the CONF menu is set to ON.