DCON protocol is a kind of application protocol based on the RS-485 network. It is special for ICPDAS DCON I/O modules, such as i-7000 series and i-87K series modules. By way of using 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 all of the I/O situations of the i-7000 and i-87K series modules connected with the RS-485 port of i-7231D. Therefore, If the i-7231D receive the command form CAN bus, it does the corresponding reactions for DCON I/O channels. In addition, we also provide the utility tool for users to configure the device parameters and build 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.