Modbus error/exception codes FX30(s) Octave

Hello All,

my external application needs to analyze logread messages from the FX30 device via SSH connection, namely, it needs to watch for Modbus error codes.
For instance I noticed when RTU unit is not connected there is a timeout message like this

May 17 15:37:50 fx30s user.err Legato: =ERR= | modbus[1653]/components T=main | mbrSlave.c mbr_SlaveRegistersRead() 112 | Failed to read from UART1/UNIT2 (addr 00002) exception -110 (Connection timed out)

it’s clear for timeout there is code -110.
Could you please disclose the list of all possible codes and their description?