CAN Bus Communication for Door Control in Cleanroom Environments

This paper introduces a part of a building automation system designed by the author to control door interlocking in cleanroom environments typically found in the pharmaceutical or semiconductor industry. The system comprises door control modules and a central module connected via Controller Area Network (CAN). The paper provides a brief explanation of the CAN communication protocol and a detailed description of the custom data format developed specifically for this application. Additionally, the hardware is briefly introduced to provide a better overview of the system. The embedded system utilizes a 16-bit PIC microcontroller with a built-in CAN controller and a significant amount of EEPROM, features leveraged in this application. CAN communication enables real-time operation and supports cable lengths of up to 500 meters with 100 nodes on the network, sufficient for most environments. With minimal network load, transmission delay is less than 1 ms, while the total network delay, including message processing, is approximately 50 ms. The simplicity, robustness, and relatively low cost of the CAN bus make it an excellent choice for real-time building automation, even in industrial environments.