Communications Installation - Wiring and cabling 
118   HC900 Process Controller Installation and User Guide  Revision 19 
    06/14 
Step  Procedure  Comments/Reference 
 
Set IP addresses and 
subnet masks. 
Default IP addresses: 
C30/C50: 192.168.1.254 and Subnet Mask of 255.255.255.0. 
C70/C75: E1: 192.168.1.254, E2: 192.168.2.254. Must be on 
different subnets. 
Links to controller communication ports 
Refer to Table 17 and the figure in Step 2 above. Port availability depends on Controller model. 
 
Table 17 – Links to Controller Communication Ports 
Controller 
Port 
/Connector 
Type 
Link Type: 
Controller to 
Cable Type  To Device/Port  Details 
RS-232 
3-plug 
connector 
Desktop or 
Laptop PC 
RS-232 Null Modem 
cable, up to 50’ 
Or 
RS-232 PC modem 
cable, up to 50’ 
Serial port of PC (w/ Null 
Modem cable)  
or  
Modem.  Refer to RS-232 
Remote Connection to PC 
Configuration Tool on page 
125. 
For Wiring details of Null 
Modem cable see Table 
19. 
RS-232 
3-plug 
connector 
Modbus master 
(controller is 
single slave) 
RS-232 Null Modem 
cable, up to 50’ 
Or 
RS-232 PC modem 
cable, up to 50’ 
RS-232 to RS-485 
converter 
Refer to device’s port 
instructions 
 
RS-232 
3-plug 
connector 
Modbus master 
(controller is one 
of multiple 
slaves) 
RS-232 to RS-485 
converter 
Refer to device’s port 
instructions 
 
RS-232 
3-plug 
connector 
Modbus slave 
network 
(controller is 
master) 
RS-232 to RS-485 
converter 
Refer to device’s port 
instructions 
 
RS-485 
3-Plug 
connector 
Operator 
interface 
Belden #9271 (or 
equivalent) 
Terminal connector of 
operator interface. (Refer 
to Table 18.) 
Connect from each CPU (A 
and B) to the OI.  
 
RS-485 
3-Plug 
connector 
Modbus master 
(controller is 
slave) 
Belden #9271 (or 
equivalent) 
Refer to device’s port 
instructions