146    HC900 Process & Safety Controller User and Installation Manual  Revision 6 
    21 April 2017 
Table 20 – Dual Network connections in Figure 78 
Connect CPU-A E1 port to Ethernet switch (3a) 
Connect CPU-B E1 port to Ethernet switch (3a) 
Connect Ethernet switch (3a) to PC Ethernet port 
Connect CPU-A E2 port to Ethernet switch (3b) 
Connect CPU-B E2 port to Ethernet switch (3b) 
Connect Ethernet switch (3b) to Ethernet port 
Ethernet switch or router/firewall for CPU-A E1 port 
Ethernet switch or router/firewall for CPU-B E1 port 
Connect CPU-A I/O port to Ethernet switch (5a) 
Connect CPU-B I/O port Ethernet switch (5b) 
Ethernet switch for CPU-A’s I/O racks 
Ethernet switch for CPU-B’s I/O racks 
Connect Ethernet switch (5a) to each I/O rack’s I/O A port 
Connect Ethernet switch (5b) to each I/O rack’s I/O B port 
Connect the (primary) Ethernet port of the 900 control Station to the Ethernet switch, which is 
assigned to port E1 of the controller CPUs 
Connect the Auxiliary Ethernet port of the 900 Control Station to the Ethernet switch, which is 
assigned to port E2 of the controller CPUs 
Connect CPU-A S1 port to PC USB port through RS-485 to USB converter (50089787-001)