Festo — CPX-4AE-4AA-H — 2021-06b
Commissioning
43
Digital output value
Current value output
Meaning
-6912
0 mA
End of output range
< -6912
0 mA
Underflow
Tab. 39: Range of values in case of fixed data format (output 4 … 20 mA)
7.5.7
Output 4 … 20 mA - scalable data format
–
Value range -32768 … 0 … 32767
–
Scalable data format -32768 … 0 … 32767
–
Scaling above the lower and upper critical limit
–
Use of the critical limits for diagnostics
–
Current value output 0 … 22 mA (for sufficiently scaled data range)
–
Current value output in case of overflow (> 22 mA): 22 mA
–
Current value output in case of underflow (< 0 mA): 0 mA
–
Conversion of the digital output value to the analogue setpoint value (current value output)
Current value = 4 + 16 x (digital output value - lower critical limit) / (upper critical limit - lower critical
limit)
Digital output value
Current value output
Meaning
> 32767
22 mA
Overflow
-32768 … 0 … 32767
4 … 20 mA
Nominal range, freely scalable
< -32768
0 mA
Underflow
Tab. 40: Range of values for scalable data format (output 4 … 20 mA)
7.5.8
Output 0 … 20 mA - fixed data format
–
Value range 0 … 20 mA
–
Data format not scalable
–
Current value output in case of overflow (> 22 mA): 22 mA
–
Current value output in case of underflow (< 0 mA): 0 mA
–
Conversion of the digital output value to the analogue setpoint value (current value output)
Current value = 20 x digital output value / 27648
Digital output value
Current value output
Meaning
> 30413
22 mA
Overflow
30413
22 mA
End of output range
27649 … 30413
> 20 mA
Overdrive range
0 … 27648
0 … 20 mA
Nominal range
0
0 mA
End of output range
< 0
0 mA
Underflow
Tab. 41: Range of values in case of fixed data format (output 0 … 20 mA)
