GE IC697CPM925 Single-slot PLC CPU Module

Microprocessor: Responsible for executing user programs, logical operations, and data processing.

Memory Unit: Contains program memory (storing user-written control programs) and data memory (storing real-time variables, register data, etc.).

Interface Circuitry: Connects to the backplane bus (for communication with local I/O) and external communication interfaces (such as Ethernet, serial ports, for networking or programming).

After the module is powered on, it first performs a hardware self-test: checking whether the microprocessor, memory, interface circuits, and backplane bus connections are normal. If a fault is detected, an alarm is triggered (such as flashing indicator lights or fault codes).

Initializes system parameters: loads default configurations (such as I/O address mapping, communication baud rate), clears temporary data areas, and prepares for operation.

Reads real-time signals from all connected local I/O modules (such as digital input modules, analog modules, special function modules) via the backplane bus.

Stores the collected input signals (such as sensor status, button signals, liquid level/temperature values) in the input image register (a dedicated area in memory, updated only during this phase). Subsequent program execution is based on this snapshot data to prevent input signal fluctuations from affecting logical judgments.

Sequentially executes the user-written control program (supporting languages such as ladder diagram, ST, FBD) starting from the first instruction.

During the operation, based on the data in the input image register and the status of internal registers (such as timers, counters, intermediate variables), it performs logical judgments (AND/OR/NOT), mathematical operations (addition, subtraction, multiplication, division, PID regulation), sequential control (step switching), etc.

The operation results are temporarily stored in the output image register (without directly driving external devices, ensuring stable output status during program execution).

After program execution is completed, the results in the output image register are sent to the output modules (such as relay output, transistor output modules) via the backplane bus.

The output modules convert electrical signals into physical actions (such as driving motors, valves, indicator lights) to control the controlled equipment.

During intervals of the scanning cycle, it synchronously processes external communications:

Monitors system status in real-time: records running time, fault information (such as I/O disconnection, communication timeout), and updates indicator light status (such as running lights, fault lights).

Compactness Optimization: Higher integration of interfaces and functions, simpler backplane bus communication logic, and reduced data transmission delay between slots.

Expansion Adaptability: Although it is a single slot, it still supports expanding multiple I/O racks via the backplane (with the cooperation of expansion modules). The scanning cycle will be slightly extended due to the increase in the number of I/O points, but the control real-time performance is maintained through the high-efficiency processor.