The customer developed a PLC based on Linux. The device is based on a System-On-Module (EXOR Embedded SOM). The device is delivered along with the BSP which supports RS-485 (accessed via tty). I/O devices connected to the PLC must be integrated in both the CODESYS IDE and CODESYS Control runtime system.
Firstly, we developed, in XML, the device description files representing the I/O devices in CODESYS. The description contains the list of configuration parameters and I/O channels (updated cyclically).
The CODESYS component handles the I/O configuration downloaded from the IDE into the PLC and communicates to the I/O device cyclically. As serial communication was to be performed in 9 bits mode, which is not supported by default by Linux, several extensions were done in the BSP together with the SOM vendor.
After development and an extensive Quality Assurance process, we delivered the project on time.