Honeywell CIU 888 Installation Manual page 26

Pin layout for 9 and 25 pins D-type connector
Signal Name
Protective ground
DCD
Signal ground
CIU 888
(female)
Prot Ground
Sign. gnd
FIGURE 3-6
3.4.3.2 Field RS232-485 Port in RS485 mode
Part No.: 4417590_Rev13
Electrical Installation - Field and Host Port Connections
Connections over short distances can be made with a "null modem"
cable. If the distance is longer than 15 m (50 ft), a modem connection
must be used. The connection to the modem depends on the type of
modem used.
Pin no.
9 Pins
Chassis
1
RXD 2
TXD 3
DTR 4
5
DSR 6
RTS 7
CTS 8
RXD
TXD
RTS
CTS
DSR
DTR
DCD
Null Modem Link
Field RS232C Port Connection Details
Refer to FIGURE 3-7 for RS-485 pin configurations and connections.
Cable requirements for RS-485 connection:
• Max. length: 1000 m (3000 ft)
• Minimum one twisted pair (typical: 50 twists per metre) with a
ground wire
• Overall shielded
• Rmax:0.12
• Cmax:119 pF/m
• Lmax:1.45 mH/m
Refer FIGURE 3-7 (A) for full duplex RS-485 connection or FIGURE 3-7
(B) when a half duplex RS-485 connection is required. For half-duplex
connect signals RXA with TXA and RXB with TXB inside the cable
connectors. Place 120
connectors.
CIU 888
Installation Manual
25 Pins
1
8
3
2
20
7
6
4
5
DTE
(female)
Prot Ground
RXD
TXD
RTS
CTS
Sign. gnd Sign. gnd
DSR
DTR
DCD
/m (per line)

resistors at the receive terminals in the cable

CIU 888
RXD
TXD
RTS
CTS
DSR
DTR
DCD
Modem Link
DCE
RXD
TXD
RTS
CTS
Sign. gnd
DSR
DTR
DCD
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