Foxboro P0917MF Control Processor

Foxboro P0917MF

• Signal Conversion and Processing: Receives analog or digital signals from sensors and transmitters, performs isolation, amplification, filtering, etc., and converts them into standard signals recognizable by the control system.

• Data Transmission and Communication: Interacts with the host computer (such as DCS system) through specific communication protocols to achieve data upload and control command reception.

• Power Industry: Applicable to automation control in power plants, such as control and monitoring of boilers, steam turbines, generators and other equipment.

• Oil and Gas Industry: Controls and optimizes various technological processes in oil extraction, refining, and natural gas processing.

• Chemical Industry: Used for reactor control, distillation column control, material conveying control, etc., in chemical production processes.

• Other Industries: Widely applied in metallurgy, glass, textile, water treatment, and other industries to realize automated control of various industrial production processes.

• High reliability, adopting a fully enclosed structure design to adapt to harsh industrial environments such as power plants and chemical plants. It has dust-proof and waterproof characteristics, which can extend service life.

• Supports redundant Node Bus (NODEBUS) and Fieldbus (FIELDBUS) to ensure the system operates stably during failures.

• Analog quantities: 0-10V, 4-20mA, PT100 (RTD), Type K thermocouple (TC), etc.

• ±0.1% FS (Full Scale), temperature drift ≤50ppm/℃.

• Modbus RTU up to 115.2kbps.

• -20℃~+60℃ (industrial grade).

• Weight: Approximately 0.5kg.

• Operating voltage: Generally 220VDC, operating current: 60.

• Input Signal Types:

• Analog quantities: Voltage (e.g., 0-10V, 1-5V), current (e.g., 4-20mA), Resistance Temperature Detector (RTD), Thermocouple (TC), etc.

• Digital quantities: Switch signals (ON/OFF), pulse signals, etc.

• Preprocessing Mechanisms:

• Signal Isolation: Achieves electrical isolation between inputs and internal circuits through optocouplers, transformers, etc., to prevent external interference or overvoltage damage to the module (e.g., isolation voltage ≥500V DC).

• Filtering and Amplification: Uses RC filter circuits to eliminate high-frequency noise, and operational amplifiers (such as OP series chips) to amplify weak signals, ensuring signal stability.

For analog inputs, the module converts continuous analog signals into discrete digital signals through an A/D converter (ADC).

• Key Parameters:

• Resolution: Such as 12-bit, 16-bit ADC, determining conversion accuracy (16-bit ADC accuracy up to 1/65536).

• Sampling rate: Sampling times per second (e.g., 100Hz) to ensure real-time capture of dynamic signals.

• Internal Processing Unit: Processes digital signals through a microprocessor (MCU) or application-specific integrated circuit (ASIC):

• Linearization correction: Performs linearization calculations on the outputs of nonlinear sensors (such as thermocouples) to restore real physical quantities (such as temperature, pressure).

• Range conversion: Maps digital values to engineering units (e.g., corresponding ADC output 0-4095 to 0-100℃).

• Fault diagnosis: Real-time monitoring of signal anomalies (such as out-of-range, open circuit), triggering alarm mechanisms.

• Output Interfaces and Protocols:

• Analog output: Converts digital signals into standard analog quantities (such as 4-20mA, 0-10V) through a digital-to-analog converter (DAC) to drive actuators.

• Digital output: Switch signals (such as relay contacts, transistor outputs) to control valves, motors, and other equipment.

• Communication interfaces: Supports protocols such as RS485, Modbus RTU, HART, etc., to interact with the host computer (e.g., send measured values, receive control commands).

• Communication Process Example:

1. The host computer sends a read command (such as a Modbus read register command).

2. After receiving the command, the module packages the processed signal data (such as temperature values) and returns it.

3. The host computer parses the data for display or closed-loop control.

• Power Input: Usually powered by 24V DC, and internally generates voltages required by each unit (such as 5V, 3.3V) through a DC-DC converter.

• Protection Functions:

• Overvoltage protection: TVS diodes suppress surge voltages (such as 60V transient protection).

• Overcurrent protection: PTC thermistors limit abnormal currents to prevent chip burnout.

• Reverse connection protection: Schottky diodes prevent circuit damage caused by reverse power polarity.

• Scenario: Temperature monitoring of chemical reactors, pipeline pressure collection.

• Working Process:
  Millivolt signal output by thermocouple → module input terminal → amplification and cold junction compensation → A/D conversion → temperature value calculation → upload to DCS via Modbus → DCS adjusts heating power based on temperature values.

• Scenario: Frequency converter speed control (4-20mA signal closed loop).

• Working Process:
  Host computer sends speed setting value (digital quantity) → module DAC converts to 4-20mA signal → drives frequency converter → frequency converter feedbacks actual speed (4-20mA) → module receives and compares with the setting value → outputs deviation signal to the host computer to adjust the control strategy.