McQuay MDS030A, Service Manual

Page: 54 / 166

48 Service Manual SM-MDS_(ii)
5.4 Confirm Indoor Dipswitch Setting
For MDS system, every unit is assigned with an address for communication and signal transmission purpose.
Both indoor and outdoor unit address need to be set manually through the dipswitch located on the PCB. Other
than address, other setting such as unit model and capacity are also set through the dipswitch. These settings
can be done during the installation process or before commissioning. It is advisable to check the settings before
commissioning starts.
The dipswitch location is different for indoor PCB MC200-C and MC201-C (Please refer to page 16 and 17).
Even though there are two types of indoor PCB, the dipswitch function is the same. For MDS indoor, there are 4
types of setting need to be determined:
a) Indoor Type
b) Indoor Capacity
c) Indoor Address
d) Indoor Function
Dipswitch 1
(SW1)
1 2 3 4 5 6
ON (1)
OFF (0)
Reserved
Auxiliary Heater
1 & 2
Water Pump
S1
Dipswitch 1 (SW1) is to determine the special function of the indoor unit. There are 2 main
special functions that can be specified in MDS indoor unit. The first function is the heater
function. This heater option is only applicable for ducted model (using wired controller) and it will
function during heating cycle or fan mode.
Locating the dipswitch S1.1 and S1.2 to ON position will give the PCB ability to control the heater
relay. The PCB is allowed to connect to 2 heaters. If only 1 heater is available, just locate S1.1
to ON position. If 2 heaters are used, both S1.1 and S1.2 need to be located to ON position.
The control algorithm of the heaters is shown in page 12.
For dipswitch S1.3 (Water Pump), it will be set to ON position for all ceiling cassette unit. The
drain pump will operate when the indoor unit is turned ON. The water pump will stop operation if
the water level sensor is in OPEN condition.
For dipswitch S1.4 until S1.6, currently is reserve for future used.
5