Option 7 - Remote Setpoint With Modbus Header Sensor And 4-20Ma Setpoint Drive - Watts Aerco BENCHMARK 750 User Manual

Benchmark 750 – 1000 Boiler User Manual - INTERNATIONAL
CHAPTER 9. BOILER SEQUENCING TECHNOLOGY
9.3.7 Option 7 - Remote Setpoint with MODBUS Header Sensor AND 4-20ma
Setpoint Drive
NOTE: Both Header Sensor AND 4-20ma Direct Drive must be wired.
Step 1: MODbus Header Sensor
1. Using Shielded pair 18 - 22 AWG cable, Connect the Temperature Transmitter (P/N 65169) terminal
Pin B to the RS485+ terminal on the I/O Box of any of the units, and Pin A of the Temperature
Transmitter to the RS485- terminal on the I/O Box of any of the units.
2. Using Shielded pair 18 - 22 AWG cable, connect the Modbus Header Temperature Sensor (P/N
24410) to pins 2 and 3 of the Temperature Transmitter.
3. Install a jumper wire between pins 1 and 2 of the Temperature Transmitter.
NOTES:
•
Polarity must be observed for the RS485 connections. The ground for the shield is at the "SHLD"
terminal in the I/O the Box.
•
The header sensor must be installed between 2 and 10 feet (0.61 and 3.1m) downstream of the
LAST Heating Boiler in the plant's supply water header.
•
There is no polarity to be observed. The ground for the shield is at the power supply ground. The
sensor end of the shield must be left free and ungrounded.
Temp Sensor P/N 24410
Step 2: Direct Wired 0-20ma or 4-20ma Wiring
1. Connect the 4-20ma or 0-20ma terminals from the Direct Drive source to the Ain+ and Ain- terminals
on the Master.
NOTES:
•
Unit's I/O Box. Shielded pair 18 - 22 AWG cable is recommended for this connection. Polarity must
be observed.
•
The ground for the shield is at the driver signal source.
OMM-0119_0A
GF-130-I
Modbus Transmitter
AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913
Ph.: 800-526-0288
I/O Box
I/O Box
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11/03/2016