Optional RS485-expansion ports in the substations
There have been used USB-RS485 -converters in earlier substations to expand more Modbus-ports for use. (The grey box in the picture under)
Those USB-RS485-converters have been supported only until FX2025A-series and earlier.
Since Fx2030-series, USB-converters haven't been supported. In Fx2030-series, there is possibility to use internal USB-COM-extension modules, instead of the external USB.
Technical bulletin 025.
In FX-3000 -series, there is possibility to use Multilink or RS-485-C extension modules.
USB-RS485 -converters are not recommended to use any new cases anymore. Its rather recommended to use MultiLink communication module for the existing substation updating needs.
Those cases, when Fx202x substation will be updated to newer model series, have to be noticed also that converter change and possible programming needs.
If there occurs some unwanted behavior in substations that uses external USB-converters, its recommended to change converters to Multilink communication module.