The PM891 processor is a single chip unit equipped with a power supply, CPU board, and unit terminal. The device includes a microprocessor and RAM memory, real-time clock, LED indicator, INIT button, and secure digital interface. The PM891 does not contain any internal batteries The PM891 has two RJ45 Ethernet ports (CN1, CN2) for connecting to the control network, and one RJ45 serial port (COM4). The COM4 port is isolated and used for configuration tools. The PM891 supports CPU redundancy for higher availability (CPU, CEX bus, communication interface, and S800 I/O).
The Communication Extension Bus (CEX-Bus) is installed on the device. The CEX-Bus is used to expand the onboard communication port through the communication interface unit. Redundant communication interfaces can be used on the CEX bus. The CEX bus interconnect unit BC810 is used to divide the CEX bus into separate parts, thereby improving its availability. The unit’s optical module bus can be used to connect up to seven clusters of S800 I/O units (each cluster contains up to 12 units). Each PM891 provides a unique Ethernet address that provides a hardware identity for the device.
Characteristics and advantages
Reliable and simple troubleshooting program
Modular, allowing for gradual expansion
IP20 protection, no case required
The controller has full EMC certification
High performance and large application memory
Use a pair of segmented CEX buses for the BC810
Built-in redundant Ethernet communication port