Johnson Controls York AYK550, User Manual

Page: 147 / 279

%**8 = 9);
YORK, A Johnson Controls Company
=9 = 3=,=* ,,2 h\J
6 782 =,2 923;@32 +?9,933=2 =,3
42@,92?2=>
Drive terminals 28
…
32 are for RS485 communications.
• Use Belden 9842 or equivalent. Belden 9842 is a dual twisted, shielded pair cable
with a wave impedance of 120
:
.
• Use one of these twisted shielded pairs for the RS485 link. Use this pair to
connect all A (-) terminals together and all B (+) terminals together.
• Use one of the wires in the other pair for the logical ground (terminal 31), leaving
one wire unused.
• Do not directly ground the RS485 network at any point. Ground all devices on the
network using their corresponding earthing terminals.
• As always, the grounding wires should not form any closed loops, and all the
devices should be earthed to a common ground.
• Connect the RS485 link in a daisy-chained bus, without dropout lines.
• To reduce noise on the network, terminate the RS485 network using 120
:
resistors at both ends of the network. Use the DIP switch to connect or disconnect
the termination resistors. See following diagram and table.
• Connect the shield at each end of the cable to a drive. On one end, connect the
shield to terminal 28, and on the other end connect to terminal 32. Do not connect
the incoming and outgoing cable shields to the same terminals, as that would
make the shielding continuous.
• For configuration information see the following:
– "Communication Set-up – EFB" below.
– "Activate Drive Control Functions – EFB" on page 144.
– The appropriate EFB protocol specific technical data. For example, "Modbus
Protocol Technical Data" on page 152.
m *3 ,4=,2 3?=,2
28 Screen
29 B (Po)
30 A (Negative -)
31 AGND
32 Screen
Terminated Terminated
Station
Station Station
Station
28 SCR
29 B
30 A
31 AGND
32 SCR
SCR
+
-
GND
RS485 Multidrop application
!#]c ,4=
Bus termination
OFF position ON position
SCR
+
-
GND
iF
&
iF
&