Nortec MES2 User Manual download pdf (Page 24)

21 | Installation

The MES2 humidifier can be operated with either On/Off controls or On/Off Safety and one

modulating input. See On/Off or Modulating Control (J10) on page 26 to configure the MES2 for

modulation. For control wiring use minimum 18 AWG and keep as short as possible. For

Modbus wiring use 18-24 AWG shielded, twisted pair 120 Ω impedance cable.

Remote fault indication is provided via a normally open relay which is closed when the controller

is in a fault condition. The dry contact may be connected to maximum of 1 amp at 24 VAC or 24

VDC.

Modbus Wiring

The optional Modbus interface board can be installed onto the MES2 control board to provide

Modbus control of the MES2. In order for Modbus control to be active a jumper must be

installed on J26 of the control board. See Modbus Configuration on page 27 for information on

configuring Modbus communication.

Figure 19: Modbus Wiring

Note: Regardless of selecting on/off or modulating control method, Nortec humidifiers

must have a closed circuit across its on/off security loop control terminal to operate.

Nortec highly recommends the use of a high limit humidistat and an air proving switch

in series for this function.

Common

Modbus

RS485

Connection

Modbus

Board

(Optional)

Note:

Requires optional Modbus board

(PN 1509592)

Use 18-24 AWG shielded, twisted pai

Connect shield at one end only.

J26 must be installed for Modbus

control.

120 Ω impedance cable.

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Nortec MES2 User Manual Page 24