I/O configuration variants
6.7 Connection of two-channel I/O to the PROFIBUS DP interface
CPU 410 Process Automation/CPU 410 SMART
86 System Manual, 05/2017, A5E31622160-AC
Use in voltage measurement
• The "wire break" diagnostics function in HW Config must not be enabled when the modules are operated with transmit-
ters.
Use in indirect current measurement
•
When using indirect current measurement, ensure a reliable connection between the sensor resistances and the actual
inputs, because a reliable wire break detection cannot be guaranteed in the case of a wire break of individual cables of
this connection.
• Use a 250 ohm resistor (measuring range 1 to 5 V) to map the current on a voltage.
Use in direct current measurement
• Suitable Zener diode: BZX85C8v2
• Circuit-specific additional error: If one module fails, the other may suddenly show an additional error of approx. 0.1%.
• Load capability of 4-wire transmitters: R
B
> 610 ohms
(determined for worst case: 1 input + 1 Zener diode at an S7 overload value of 24 mA to R
B
= (R
E
* I
max
+ U
z max
) / I
max)
• Input voltage in the circuit when operating with a 2-wire transmitter: U
e-2w
< 15 V
(determined for worst case: 1 input + 1 Zener diode at an S7 overload value of 24 mA to U
e-2w
= R
E
* I
max
+ U
z max
)
Use in voltage measurement
• The "wire break" diagnostics function in HW Config must not be enabled either the modules are operated with transmit-
ters or when thermocouples are connected.
Use in indirect current measurement
• Use a 250 ohm resistor (measuring range 1 to 5 V) to map the current on a voltage.
Use in direct current measurement
• Suitable Zener diode: BZX85C8v2
• Load capability of 4-wire transmitters: R
B
> 610 ohms
(determined for worst case: 1 input + 1 Zener diode at an S7 overload value of 24 mA to R
B
= (R
E
* I
max
+ U
z max
) / I
max)
• Input voltage in the circuit when operating with a 2-wire transmitter:
U
e-2w
< 15 V (determined for worst case: 1 input + 1 Zener diode at an S7 overload value of 24 mA to U
e-2w
= R
E
* I
max
+
U
z max
)
You may use this module only with redundant sensors.
You can use this module with Version 3.5 or higher of FB 450 "RED_IN" in the library "Redundant IO MGP" and Version
5.8 or higher of FB 450 "RED_IN" in the library "Redundant IO CGP" V50.
Observe the following when measuring temperatures by means of thermocouples and assigned redundancy:
The value specified in "Redundancy" under "Tolerance window" is always based on 2765 °C. For example, a check is
made for a tolerance of 27 degrees when "1" is entered and 138 degrees when "5" is entered.
A FW update is not possible in redundant operation
An online calibration is not possible in redundant operation.
Use in voltage measurement
• The "wire break" diagnostics function in HW Config must not be enabled when the modules are operated with thermo-
couples.
Use in indirect current measurement
• Due to the maximum voltage range +/- 1 V, the indirect current measurement can be carried out exclusively via a 50
ohm resistor. Mapping that conforms to the system is only possible for the area +/- 20 mA.