York YPAL 060, YPAL 061, YPAL 050, YPAL 051 VAV Heat Relay Output, Supply Air Temperature Reset

VAV Heat Relay Output

This is a 24 VDC output that is turned on when the unit is in the heating mode. The field can use this as a signal to trigger the opening of the VAV boxes for heating operation. This feature uses two ¼ inch male tabs identified as (VAV OPEN +) and (VAV OPEN -) on the Simplicity control board.

Supply Air Temperature Reset

An external 0 to 10 VDC input can be applied to terminals (REM+) and (REM-) at terminal block P19 on the Simplicity control board to reset the supply air temperature set point for VAV operation. The units follows interprets the voltage input as follows:

Below 1.0 VDC – the blower is de-energized

Below 1.5 VDC – the cooling and heating is disabled

At 2.0 VDC – the control uses the lower set point

Between 2.0 VDC and 10 VDC the change in set point is proportional to the change in voltage.

At 10.0 VDC – the control uses the upper set point

FORM 100.50-NOM6 (1207)

COMMUNICATION

The Simplicity Unit Controller is designed to communicate using Modbus Client protocol. Through the use of a ModLINC translator the unit can also communicate using BACnet MS/TP protocol.

Through the use of a FREEnet Serial or USB adapter 2 the Simplicity Unit Controller can be connected directly

to a computer. Multiple units can be daisy chained together and through the use of the adapter connected to a computer or a network. This allows remote monitoring of the unit as well as the ability to change settings and options from a remote location.

Connection to the unit is done through either of two RS-485 connections. The P4 terminal block has screw connections with terminal A being the – and terminal B being the +. The P5 connecter is designed to allow the mating connector from the FREEnet Serial or USB adapter to be plugged in.

See Table 6-1 for parameter points list.

DIRTY FILTER SWITCH

On units with a dirty filter switch option, an adjustable differential pressure switch is installed to monitor the pressure drop across the filters. When the pressure drop across the filters exceeds the setting of the switch, the switch closes sending a 24-volt signal to the Unit Controller. The Unit Controller posts a warning in the service memory buffer; but will not shut down the unit.

JOHNSON CONTROLS 35