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8
3.8 - Connections at the user terminal block
Connections available at the user terminal block may vary
depending on the selected options.
3.8.2 - Volt-free on/off contact
If the unit operates in Remote mode, the on/off contacts is
as follows:
With multiplexing
Off
Cooling
On/Off contact
open
closed
Legend:
1. Off: Unit is stopped
2. Cooling: Unit is allowed to start in Cooling
3.8.3 - Volt-free setpoint selection contact
This dry contact input is used to switch between setpoints.
It is active only when the control is in Remote mode.
Cooling
Setpoint 1
Setpoint 2
Setpoint selection contact
open
closed
3.8.4 - Volt-free demand limit selection contact
Up to two dry contacts can be used to limit unit capacity.
Note that the second contact is available for units with the
energy management module.
Capacity limitation with two contacts is as follows:
100%
Limit 1
Limit 2
Limit 3
Demand limit 1 contact
open
closed
open
closed
Demand limit 2 contact
open
open
closed
closed
The limits are defined in the SETPOINT menu.
3.8.1 - Terminal block connections
Some contacts can be accessed only when the unit
operates in Remote mode.
The following table summarises the connections at the
user terminal block.
Terminal block connections
Description
Board
Input/Output
type
Channel/
Connector Remarks
On/Off switch
SIOB, circuit A
DI-01
J1
Used for the unit on/off control if the unit is in Remote mode
Second setpoint switch
SIOB, circuit A
DI-02
J1
The contact is taken into consideration if the unit is in Remote mode
Demand limit switch 1
SIOB, circuit A
DI-03
J1
Used to control demand limit. See section 6.5
Alarm relay
SIOB, circuit A
DO-05
J23
Indicates alarms
Running relay
SIOB, circuit A
DO-06
J22
Indicates if the unit is ready to start or operating
Optional
Occupancy override switch
NRCP2, EMM
DI
Ch 08
Used to switch between occupied (closed contact) and unoccupied
mode (open contact)
Capacity limit switch input 2
NRCP2, EMM
DI
Ch 09
Used to control demand limit
Customer interlock
NRCP2, EMM
DI
Ch 10
Used for the customer safety loops (if the contact is closed, the
chiller is stopped)
Ice done contact
NRCP2, EMM
DI
Ch 11a
Used to control the setpoint according to the occupancy schedule