The GFX4-MOD module can be installed inside GFX4/GFXTERMO4 products and expands communication by means of the Modvus RTU protocol. The module has two communication channels: 
• the first channel is a serial port with Modbus RTU protocol, and connects 32 GFX4/GFXTERMO4 devices (without repeater); 
• the second channel is a serial port with Modbus RTU slave protocol, and lets you connect to a Modbus RTU Master.
The node address is assigned by means of the two rotary switches (0...99) on the product that houses the module. The network Master (typically a PLC) recognizes the slave node by means of this address. The slave node recognized by the Master consists of the GFX4/GFXTERMO4 that houses the module plus the GFX4/GFXTERMO4 products connected to the Modbus serial port. The expansion can be installed when the above-mentioned products are ordered or at a later date.