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Benchmark 5000-6000 Boiler Installation & Startup Manual
SECTION 6: BOILER SEQUENCING TECHNOLOGY
6.3.2 OPTION 2 - Constant Setpoint With Modbus Wired Header
Sensor
OPTION 2 - Constant Setpoint With Modbus Wired Header Sensor Instructions
Step 1: MODbus Header Sensor Wiring
Using Shielded pair 18 - 22 AWG cable, connect the Temperature Transmitter (P/N 65169)
1.
terminal Pin B to the RS485+ terminal on the I/O Box of any of the Boiler units, and Pin A of
the Temperature Transmitter to the RS485- terminal on the I/O Box of any of the Boiler
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 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: Configure ALL C-More Units
On ALL Boilers:
1. Go to the Configuration menu and set the BST Menu item to Enabled.
2. Go to the Boiler Sequencing Menu and set the BST Mode item to BST Client (for now).
On MANAGER only:
3. Go to the BST Setpoint item and enter the desired Setpoint.
4. Go to the BST Setup Menu item and set to Enabled.
5. Go to the BST Setpoint Mode item and select Constant Setpoint.
6. Go to the Head Temp Source item and select Network.
7. Go to the Header Temp Addr item and enter the Modbus Address (240).
8. Go to the Header Temp Point item and enter the Modbus Point (14).
When ALL C-More units have been configured:
9. Go to the Boiler Sequencing Menu of the Manager unit and set the BST Mode item to BST
MANAGER.
OMM-0123_E • GF-207 • 12/17/2019
MODBUS TRANSMITTER
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
I/O BOX
Page 80 of 95
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