Honeywell DCP551 Mark ΙΙ User Manual page 46

3-wire system RS-485 connection diagram
Attach 1/2W or greater terminating resistances of 150Ω ±5% at each end of the commu-
nications lines. Ground the shield FGs at one end in one location, not at both ends.
When only three RS-485 terminals are provided, the areas designated with an asterisk
(*) are connected internally.
Master station
HANDLING PRECAUTIONS
• Be sure to connect SG terminals each other. Failure to do so might cause
Terminating resistor
Shield
RDA
RDB
SDA
*
*
SDB
SG
FG
Shield
Shield
Terminating resistor
unstable communications.
Chapter 4. WIRING
,+2##
Slave station side
SDA
60
SDB
61
RDA
62
RDB
63
SG
64
FG
,+2##
Slave station side
SDA
60
SDB
61
RDA
62
RDB
63
SG
64
FG
,+2##
Slave station side
SDA
60
SDB
61
RDA
62
RDB
63
SG
64
FG
4-15