Specification Summary – Compliance and Functional Scope
The CPU integrates a PROFINET interface with two ports, shared-device capability, and auto-crossover. PROFIBUS communication is achieved via the CM 1243-5 module. MODBUS TCP communication is supported both as client and server. AS-Interface is also supported. This set of protocols ensures broad compatibility with existing fieldbus architectures, as evidenced by the datasheet.
Analog Inputs and Process Value Handling
The CPU includes 2 analog input channels configurable for 0 to +10 V or 0 to 20 mA, with adjustable measuring range per channel. This eliminates the need for external signal-conditioning modules for common process transmitters, simplifying panel wiring and reducing component count. Digital input thresholds are defined per specification: signal '1' at 15 V DC at 2.5 mA, signal '0' at 5 V DC at 1 mA. The 24 V DC supply requirement is L+ minus 4 V DC minimum. For audit purposes, these thresholds should be compared against the output characteristics of the connected sensors to guarantee switching reliability.
Memory, Backup, and Forcing Capabilities
Integrated load memory is 4 Mbyte. The bit memory address area is limited to 8 kbyte. A typical backup time of 480 h is provided for retentive data. The CPU supports forcing of inputs and outputs, which is useful during commissioning and troubleshooting. The module supports full I/O monitoring: inputs/outputs, memory bits, data blocks, distributed I/Os, timers, and counters can be observed and modified. The number of program blocks is limited only by the available RAM for code.