This paper describes architecture and development of an open application programming interface (API) prototype for injection molding machines (IMMs), useable for sensor and machine/process data logging and setting necessary process parameter values. The API is based on PCMEF (presentation, control, domain and foundation) architectural framework and OSI 7 layer communication model. The interface allows to retrieve values of up to 97 machine and process parameters. It also includes a module for acquisition of data from additional sensors such as pressure and temperature sensors installed in the mold. Industrial Raspberry Pi (RevPi) is used to perform analog-to-digital signal conversion and makes sensors data accessible via the API. Logging of different parameters from the machine and from sensors is synchronized and sampling frequency can be adjusted if necessary. Depending on chosen frequency, the system can provide real-time or soft real-time communication. The interface allows to build a distributed computer-based system, which gives benefit over the use of a PLC system with respect to Industry 4.0 standards.