Most RS-232 devices don't support device addressing. The ICPDAS I-752N series assigns a unique address to any RS-232 device installed on an RS-485 network. When the Host PC sends a command with a device address to the RS-485 network, the destination I-752N module will remove the address field, and then pass the other commands to its local RS-232 devices. The response from the local RS-232 devices will be returned to the Host PC via the I-752N module. ICP DAS I-752N products are unique in that they are a Master-type converter that use our R.O.C. Patent 086674, while most other converters are a Slave-type, which cannot operate without a Host PC. In real industrial applications, many users are not satisfied with Slave-type converters as they cannot be adapted to individual requirements.