Multiple Chiller Setup - Daikin DWSC079 Installation, Operation And Maintenance Manual

Multiple Chiller Setup

Single compressor chillers DWSC and dual compressor chillers DWDC 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. 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
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.
With no pLAN connections between chillers, disconnect chiller control power and set the DIP switches as
1.
shown in Table 11.
With all manual switches off, turn on control power to each chiller and set each OITS address (see Note 2 on
2.
page 36).
Verify correct nodes on each OITS Service Screen.
3.
Connect chillers together (pLAN, RS485 wiring) as shown in Figure 16. The first chiller in the connection can
4.
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.
Verify correct nodes on each OITS Service Screen.
5.
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