Table of Contents
Advertisement
Multiple Chiller Setup
Interconnecting MicroTech II pLAN RS485 wiring should be installed by the installing
contractor prior to start-up. The Daikin start-up technician will check the connections
and make the necessary set point settings.
1. With no pLAN connections between chillers, disconnect chiller control power and
2. With all manual switches off, turn on control power to each chiller and set each
3. Verify correct nodes on each OITS Service Screen.
4. Connect chillers together (pLAN, RS485 wiring) as shown in Figure 16. The first
5. Verify correct nodes on each OITS Service Screen.
34
Single compressor chillers DWSC and dual compressor chillers DWDC and DWCC
have their main control components factory wired to an internal pLAN network so that
the components can communicate with each other, within the chiller itself.
On multi-chiller applications, up to four chillers, either single, or dual compressor, can
be interconnected by this internal pLAN. All that is required is simple field RS485
interconnecting wiring, the addition of accessory communication isolation board(s)
485OPDR (Daikin P/N 330276202), and some MicroTech II control settings (see
special DWCC instructions at the end of this section). The 485OPDR isolation board
can be purchased with the unit or separately, during or after chiller installation. The
number of chillers minus one boards are required.
pLAN Setup
set the DIP switches as shown in Table 11.
OITS address (see Note 2 on page 35).
chiller in the connection can be designated as Chiller A. The isolation board is
attached to the DIN rail adjacent to the Chiller A unit controller. The isolation board
has a pigtail that is plugged into J10 on the controller. Most chillers will already
have a universal communication module (UCM) that connects the controller to the
toucDHSCreen already plugged onto J10. If this is the case, plug the isolation
module pigtail into the empty RJ11 pLAN port on the UCM. This is equivalent to
plugging into the unit controller directly.
Next, interconnecting wiring is needed between Chiller A and Chiller B.
Two Chillers: If only two chillers are to be connected, Belden M9841 (RS 485 Spec
Cable) is wired from the 485OPDR isolation board (terminals A, B, and C) on
Chiller A to the J11 port on the unit controller of Chiller B. At J11, the shield
connects to GND, the blue/white wire to the (+) connection, and the white/blue to
the (-) connection.
Note that Chiller B does not have an isolation board. The last chiller (B in this case)
to be connected does not need an isolation board.
Three or More Chillers: If three or more chillers are to be connected, the
interconnecting wiring is still made to Chiller B's J11 port. The second chiller
(Chiller B) must have a 485OPDR isolator board that will be plugged into Chiller
B's UCM pLAN port. Chiller B will look like Chiller A.
The wiring from Chiller B to Chiller C will be the same as A to B. That is, Belden
cable connects from A, B, and C on B's 485OPDR board to chiller C's L11 port.
Chiller C has no 485OPDR isolation board.
The procedure is repeated to the fourth chiller if four chillers are interconnected.
Centrifugal Chillers
D-EIMWC00804-14EN
Advertisement
Table of Contents
