1. KL3224 - 4-channel analog input terminal PT1000, Ni1000
2. Access from the user program
3. Control and status byte
4. Compensation

Compensation

Implemented linear equation

Y[Ω] = (X_Adc * G + B_h) * A_h + 100 Ω

Hence:

B_h consists of a component that depends on the gain of the A/D converter and a constant for calculating the axis offset of 100 Ω. The gain-dependent component calculates the offset of the external components (the offset of the component can be varied via adjustable amplification). This procedure is necessary, because compensation at 0 Ω is technically not possible. The line is therefore compensated around the point 100 Ω (offset to the point and rotated around this point).

B_h: (B_off * G + B_100)

• Offset compensation should therefore be carried out for PT100 at 100 Ω (or PT1000 at 1000 Ω).
• Gain compensation is then carried out independently of the offset, e.g., at 300 Ω. 300 Ω corresponds to 557.7 °C = 0x15C9