METSO PDP401 Optical Isolator

PDP401 information transmission using CAN communication protocol, the communication medium using twisted-pair cable. Since the CAN bus is based on the encoding of sent messages and does not encode the CAN control nodes, the system is more expandable, while the addition or deletion of control nodes on the CAN bus will not have any effect on the remaining nodes of the system.

The MCU of PDP401 node controller can choose microprocessor with SPI interface or microprocessor without SPI interface. This system uses a microprocessor without SPI interface. the PDP401 can be directly connected to the SPI interface of the CAN controller through the P1 port, and software algorithms are used to implement the SPI interface protocol. the CAN bus transceiver PDP401 interfaces with the physical bus. If you need to further improve the system’s anti-interference ability, you can add an opto-isolator in the MPDP401.

In this paper, PDP401 mainly takes the interrupt mode to receive and send bus data. The main sequence of the whole system provides two kinds of interrupts: timer interrupt and external interrupt. The interrupt subroutine of the timer interrupt is mainly responsible for processing the A/D data from analogue channels AINO to AIN7, sending the “data send request command” to the MCP25lO, and sending the data. The interrupt processing subroutine of the external interrupt mainly consists of the CAN bus error handling subroutine and the data receiving subroutine.