SIRIUS 3RA28 function modules for mounting on 3RT2 contactors   
7.6 Mounting 
  SIRIUS Innovations 
664  System Manual, 01/2011, A8E56203870002-03 
Step  Operating instruction  Figure 
5  Push the interlock slide down with a 
screwdriver until it engages. 
6  Insert the coded module connector into 
the slot in the correct position from 
above until the module connector 
engages in the locking mechanism. 
7  To complete the process, lock the 
module connector.