GDC to JNIOR connection not working
If the JNIOR series 4, models 410, 412 or 414, is not working with the GDC then check to make sure MODBUS is enabled. The built-in library for the JNIOR on the GDC server uses MODBUS.
The series 3 enabled the MODBUS server by default. The MODBUS server is an optional application that needs to be enabled on the series 4. You can look at the following links for more information