Question:
When at the analog input AIN1 (X6/1, X6/2) a master current of up to 20 mA is selected and the jumper setting at X3 is correspondingly modified, why does the value shown internally at the function block AIN1 is only 50 % of the applied set value (e. g. in case of 20 mA input signal an internal setpoint of 50 %)?
Answer:
The switch-over from voltage to current master value by means of the jumper setting at X3 switches a current load 242 Ω in parallel to the terminals X6/1 and X6/2.
Master voltage/potentiometer:
- Jumper X3 in the lower position (default setting range)
Master current:
- Jumper X3 in the upper position
The resolution for the master current reduces from (11 Bit + sign) to (10 Bit + sign). The signal conditioning in the function block AIN1 must correspondingly compensate the loss of the resolution by increasing the gain via code
C0034/000. If the analog input 1 is supposed to read a master current correctly, you can select the current-setting range with code
C0034/000 and automatically execute the adaptation of the gain:
- For -20 … +20 mA: C0034 = 2
- For 4 … 20 mA: C0034 = 1 (can be applied unipolar only, if it falls below 2 mA the error message Sd5 is set)
Jumper setting X3 and C0034/000 must therefore always be set on the same range, as otherwise the drive controller will interprete the analog input signal incorrectly!
An adaptation via the AIN1-GAIN function block input is also possible, it is, however, intended to be used for signal-shaping by the user and should not be used for this purpose.
