Finish Installation - Emerson MRLDS-250 Installation And Operation Manual

Infrared gas detector

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Installation and operation manual (30 pages)

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Table Of Contents

Table of Contents

CAUTION: Connect the RS-485 cable

shield to pin 9 (board ground).

NOTE: Selection of the MODBUS

Address and Baud Rate is completed

through the gas detector setup menu,

described later. No jumpers or

hardware switch settings are required to

configure the MODBUS communications

network. This is done electronically from the front

panel display.

NOTE: For MODBUS

communications with the MRLDS-

250, the default communications

parameters are as follows.

Baud rate = 9600

Parity = no parity

Stop bits = 1

Confirm that all devices on the MODBUS

communications network (including a

Building Management System) are configured

similarly.

If the MRLDS-250 is at the end of the RS-485

network, be sure to set the RS-485 terminator on the

printed circuit board (PCB) to IN. This applies a

terminating resistor to the end of the wires per the

requirements of the RS-485 protocol. The terminator

should be set to OUT for all other installation

conditions.

NOTE: Be sure to enable the

termination resistor on the device at

each end of the network (See Figure

3-7). This includes the Building

Management System (if used).

CAUTION: Care should be

exercised when changing the

terminator switch. Before powering

the gas detector, use a fine pointed

device or paper clip to slide the

switch position. Do not apply force to the switch

or push on the switch with any device. The

switch changes position up and down along the

access slot direction.

12 • MRLDS-250 Infrared Gas Detector I&O Manual

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Figure 3-7 - Setting Network Termination Resistors

3.6.