Honeywell CIU 888 Installation Manual page 25

FIGURE 3-5
3.4.3.1 Field RS232-485 Port in RS232C mode [Part of a future release]
3 - 6
Electrical Installation - Field and Host Port Connections
TRL/2 Field Bus Connection:
TRL/2 Field Bus connection
It is recommended to use the following cable specifications for effective
results.
Two conductors, shielded twisted pair

Cmax: 668 nF (18 AWG); 4 km

Rmax: 98.4

Lmax: 1.96 mH (18 AWG);4 km

Length (max): 4 km, stub not > 100 m

Num. of instruments (max): 1 Parent, 8 children

Gauge (All are shielded twisted pair):

• Belden 88760 (18 AWG) 4 km
• Belden 8762 (20 AWG) 3 km
• Belden 88761 (22 AWG) 2 km
• Belden 88641 (24 AWG) 1 km
• Stub not > 100 meters
No of strands: 7 or 19 (or more, higher => better performance)

Shielded connection: Earthed towards Host system (FCU/FBM)

3.4.3 Field RS232-485 Port
A RS232-485
(Communications Interface Unit) can be placed in any of the option slots
1 to 6. These ports have galvanic isolation.
See the section 3.3 "CIU 888 Interface Summary" for locating the ports.
Refer to FIGURE 3-6 for RS-232C pin configuration and connections.
Cable requirements for RS232 connections:
• Max. length: 15 m (50 ft)
• Overall shielded
CIU 888
Installation Manual
(22 AWG); 2 km

Field Board for connection to a
Part No.: 4417590_Rev13
CIU 888