DCON protocol is a kind of application protocol based on the RS-485 network. It is designed for ICPDAS DCON I/O modules, such as i-7000 series and i-87K series modules. By using the i-7231D to convert the electric signals and messages, the DCON I/O modules can be upgraded to the CANopen protocol based on the CAN bus. For CANopen protocol application, the i-7231D is a CANopen slave device. So, it can produce or consume the PDO messages, receive the SDO message with proper responses, and deal with the NMT messages from NMT master. For DCON protocol application, it is a DCON master device, and it will collect the I/O status of all the i-7000 and i-87K series modules connected to the RS-485 port of i-7231D. Therefore, If the i-7231D receive the command from CAN bus, it does the corresponding reactions for DCON I/O channels. In addition, a utility tool is available for users to configure the device parameters and build an EDS file for the CANopen slave device. Therefore, users can easily apply i-7k and i-87K IO modules in any CANopen master interface with EDS file via the i-7231D.