HC900 Control System Architectures -  
10    HC900 Process & Safety Controller Safety Manual  Revision 1.9 
    01/14 
Table 2 – Descriptions of Major Components 
Key No.  Component 
Name 
Description  Source 
1  Controller 
(Local) Rack 
Includes: Rack, Power Supply, Controller Module, 
and I/O modules 
Honeywell 
2  I/O Expansion 
Rack 
(C50S/C70S 
CPUs only) 
(Optional) Includes: Rack, Power Supply, Scanner 
Module, and I/O modules  
Honeywell 
3  Operator 
Interface 
900 Control Station operator interface 
communicates via Ethernet or RS-485 serial link 
Honeywell 
4  PC 
Configuration 
Tool 
(Optional) PC (laptop or desktop) connects to 
RS-485 or Ethernet port(s) on any (one) Controller 
module.  Includes Honeywell Designer Software 
(configuration software).   
PC & USB to RS485 
convertors are from 
third-party suppliers.  
Configuration software 
is from Honeywell. 
5   HMI (Human-
Machine 
Interface) 
(Optional) PC link to Ethernet network, which may 
include other HMIs, other HC900 Controllers, and 
other networks (including Internet). 
Typically includes HMI operating software. 
May also include Designer Software (configuration 
tool and utility software). 
PC is from third-party 
supplier.  HMI software 
is available from 
Honeywell (PlantScape 
or SpecView32) or 
from third-party 
supplier. 
6  Ethernet 
100Base-T 
Switch  
Enables connection of the private Ethernet 
100Base-T port on a (C50S/C70S CPU only) 
Controller Module to the (S50S) Scanner modules 
on 2, 3, or 4 I/O Expansion racks. (If a single I/O 
expansion rack is connected directly to a Controller 
Module, the Switch is not required.)  
Honeywell Qualified 
Switch from Honeywell 
or third- party suppliers 
6a  Ethernet 
10/100Base-T  
Switch or 
Router 
Enables inter-connection of several 10/100Base-T 
Ethernet devices in an Ethernet network.  Devices 
include other HC900 Controllers, HMIs, and can 
also include routers, brouters, servers, and other 
devices in wider networks. 
Third-party suppliers. 
7  Shielded CAT5 
Ethernet cable 
Connects I/O expansion racks (S50S only) to 
controllers (C50/C70 CPU only) and/or to 
10/100baseT Ethernet switches. 
Honeywell  or Third-
party suppliers 
Fiber Optics 
Cable 
Controller to remote rack distance up to 750m 
(2460 ft.) with one fiber cable. Distances up to 
1500m (4920 ft.) are possible with a fiber switch 
used as a repeater at the midpoint. 
8   Shielded CAT5 
Ethernet cable 
Connects devices in Ethernet Open Connectivity 
network to 900 Control Stations and PC SCADA 
applications. 
Honeywell  or Third-
party suppliers 
10  RS-485 cable  Shielded twisted pair cable connects Isolated 
Controller port to field devices or  PC with RS-485 
convertor 
Honeywell  or Third-
party suppliers