Shield (Shld & Shld); Analog Out; Rs485 Comm (+, Gnd, & -); Rs232 Comm (Txd & Rxd) - Watts Aerco Benchmark OMM-0124 Installation And Start-Up Manual

Natural gas, propane gas and dual fuel fired modulating & condensing boilers
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Benchmark 5000-6000 Boiler Installation & Startup Manual
SECTION 2: INSTALLATION
(b) If the valve fails with the Valve Stuck Closed fault, the "Valve Stuck Closed" message
will be displayed and the unit will shut down.
NOTE:
If the Valve Feedback option is used, Shorting Jumper MUST be inserted on JP2 on the I/O
Board (see Figure 2-14, above).
2.11.7 SHIELD (SHLD & SHLD)
The SHIELD terminals are used to terminate any shields used on sensor wires connected to the
unit. Shields must only be connected to these terminals.

2.11.8 ANALOG OUT

On current model Benchmark units, the default setting in the C-More Controller is Valve Position
0-10v, and behaves as follows:
0-10VDC must be selected for the voltage output used by the Controller to modulate the
combustion blower via the I/O Box terminals labeled VFD/BLOWER (Section 2.11.11).
If Boiler Sequencing Technology (BST) is enabled, the Analog Output terminals are used
to drive the isolation valve. A 0-20 mA signal is used: 20 mA = closed, 0 mA = open.
NOTE:
When driving an isolation valve, shorting jumper #JP2 MUST be installed on the I/O Board.
On older legacy Benchmark units, the two ANALOG OUT terminals may be used to monitor
Setpoint, Outlet Temperature, Valve Position 4-20 mA, Valve Position 0-10v or be set to OFF.
2.11.9 RS485 Comm (+, GND, & -)
The three RS-485 communication terminals are used when the boiler plant is being controlled
by an Energy Management System (EMS) or an AERCO Control System (ACS) using Modbus
(RS485) communication.
2.11.10 RS232 Comm (TxD & RxD)
As of Firmware version 4.0 and above, these terminals are used only by factory-trained
personnel to monitor onAER communications via a portable computer.
2.11.11 VFD/Blower (0-10 & AGND)
The two VFD/BLOWER terminals, 0-10 and AGND, send an analog signal to control the blower
speed.

2.11.12 Interlocks

The unit has two interlock circuits for interfacing with Energy Management Systems and
auxiliary equipment, such as pumps, louvers or other accessories. These interlocks are called
the Remote Interlock and Delayed Interlock (REMOTE INTL'K IN and DELAYED INTL'K IN in
Figure 2-14). Both interlocks, described below, are factory wired in the closed position using
jumpers.
OMM-0123_E • GF-207 • 12/17/2019
Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
Page 29 of 95

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