Modbus TCP & Modbus RTU Industrial PLC Protocol

// Modbus TCP Industrial Register Layout (Port 502)
public enum ModbusRfidMap : ushort
{
    // Coils (Read/Write 0x)
    TriggerReadStart    = 0x0001,  // PLC sets 1 to begin RF interrogation
    GreenStackLight     = 0x0002,  // Set 1 on successful ERP match
    RedStackLightBuzzer = 0x0003,  // Set 1 on barcode mismatch / ghost tag
    PneumaticDiverter   = 0x0004,  // Set 1 to push bad carton to reject lane

    // Discrete Inputs (Read-Only 1x)
    PhotoEyeSensorEntry = 0x0001,  // High when carton cuts entry laser beam
    PhotoEyeSensorExit  = 0x0002,  // High when carton clears gate

    // Input Registers (Read-Only 3x)
    LastReadTagCount    = 30001,   // Total tags decoded during last trigger cycle
    ReaderTemperatureC  = 30002,   // Ambient board temperature

    // Holding Registers (Read/Write 4x)
    RfTransmitPowerDbm  = 40001,   // Transmit power (100 to 300 = 10.0 to 30.0 dBm)
    FilterDwellTimeMs   = 40002    // Minimum required tag RSSI persistence (ms)
}