Honeywell CIU 888 Installation Manual page 27

A) Full Duplex Connection
CIU 888
(female)
Prot Ground
TXA
TXB
RXA
RXB
Sign. gnd
TXA
TXB
RXA
RXB
Sign. gnd
(n)
CIU 888
(female)
FIGURE 3-7
3 - 8
Electrical Installation - Field and Host Port Connections
Direct connection can only be made if the CIU 888 and the DTE (CIU
888 or host computer system) are grounded at the same point.
In all other cases, ensure there is at least a proper galvanic isolation at
the DTE side. Galvanic isolation can also be obtained by means of a
modem connection between the CIU 888 and the host computer
system.
DTE/DCE
RXA
120E
RXB
TXA
120 E
TXB
Sign. gnd
C) Half Duplex – Multi-drop connection
120 E
TXA
TXB
RXA
RXB
Sign. gnd
(1)
CIU 888
(female)
Field RS485 Port Connection Details
CIU 888
Installation Manual
B) Half Duplex Connection
CIU 888
(female)
Prot Ground
TXA
TXB
RXA
120 E
RXB
Sign. gnd
TXA
TXB
RXA
RXB
Sign. gnd
(2)
CIU 888
(female)
DTE/DCE
RXA
120 E
RXB
TXA
TXB
Sign. gnd
RXA
120 E
RXB
TXA
TXB
Sign. gnd
Pin layout for 9 pins D-type
connector
Signal Name 9 Pins
Protective ground Chassis
RXA 2
RXB 8
TXA 3
TXB 7
Signal ground 5
Part No.: 4417590_Rev13