CoolEx is a Modbus RTU IO adapter with analog, digital and PWM inputs and outputs. CoolEx can be used in conjunction with Programmable Logic Controller (PLC) or any other Modbus master that requires some extra I/O or special IO functionality. CoolEx is controlled by master by means of standard Modbus requests defined in “Modbus Application Protocol Specification“. CoolEx physical connection to MODBUS is Two-wire EIA/TIA-485 standard interface recommended by “Modbus over Serial Line Specification and Implementation Guide”. A number of CoolEx devices can be connected to single 2W-bus. To utilize CoolEx with TCP/IP Modbus master over Ethernet network MODBUS 485RTU/TCP Gateway can be used.