I/O configuration variants   
6.7 Connection of two-channel I/O to the PROFIBUS DP interface 
  CPU 410 Process Automation/CPU 410 SMART 
84  System Manual, 05/2017, A5E31622160-AC 
A complete list of all modules released for SIMATIC PCS 7 V9.0 can be found in the 
SIMATIC PCS 7 technical documentation, see Technical documentation. 
Table 6- 6  Signal modules for redundancy 
Redundant DI dual-channel 
DI16xDC 24 V, interrupt  6ES7 321-7BH00-0AB0 
In the event of an error on one channel, the entire group (2 channels) is passivated. When using the module with HF index, 
only the faulty channel is passivated in the event of a channel error. 
Use with non-redundant encoder 
•  This module supports the "wire break" diagnostic function. To implement this function, make sure that a total current 
between 2.4 mA and 4.9 mA flows even at signal state "0" when you use an encoder that is evaluated at two inputs in 
parallel. 
 
You achieve this by connecting a resistor across the encoder. Its value depends on the type of switch and usually 
ranges between 6800 and 8200 ohms for contacts.  
 
For BEROS, calculate the resistance using the following formula: 
(30 V / (4.9 mA - I_R_Bero) < R < (20 V / (2.4 mA - I_R_Bero) 
In some system states, it is possible that an incorrect value of the first module is read in briefly when the front connector of 
the second module is removed. This is prevented by using series diodes. 
In some system states, it is possible that an incorrect value of the first module is read in briefly when the front connector of 
the second module is removed. This is prevented by using series diodes. 
You cannot use the module in redundant operation for applications in hazardous areas. 
Use with non-redundant encoder 
•  You can only connect 2-wire NAMUR encoders or contact makers. 
•  Equipotential bonding of the encoder circuit should always be at one point only (preferably encoder negative). 
•  When selecting encoders, compare their 
properties with the specified input characteristics. Remember that this function 
must always be available, regardless of whether you are using one or two inputs. 
Use with non-redundant encoder 
•  Equipotential bonding of the encoder circuit should always be at one point only (preferably encoder negative). 
•  Operate the two redundant modules on a common load power supply. 
•  When selecting encoders, compare their properties with the specified input characteristics. Remember that this function 
must always be available, regardless of whether you are using one or two inputs. 
DI 24xDC 24 V  6ES7326-1BK01-0AB0 
F module in standard mode 
F module in standard mode