Overview of Primary Product

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RS232/RS485 Communication Interfaces
Terminals 5 and 6 on Multi-Burner Control terminal strip J7 provide a serial output communication
interface for remotely monitoring the system sequence and status using a terminal or a modem; refer
to later section for the types of messages sent by the Multi-Burner Control.
The communications protocol is 8 bit, no parity, 1 stop bit and1200 baud. Multi-Burner Control
model MB-632S is provided as a RS232 interface. Multi-Burner Control model MB-685S is pro-
vided as a RS485 interface.
Transmission of messages from the Multi-Burner out the RS232/RS485 interface is turned ON by
default at power up and at the completion of each burner cycle. Transmission of ALL messages out
the RS232/RS485 port can be turned OFF for the remainder of the current burner cycle by sending a
space character (<SP>=ASCII Hex 20). Messages can be turned back ON by sending a carriage
return (<CR>=ASCII Hex 0D) from the terminal.
Sending a CTRL-E (<ENQ>=ASCII Hex 05) access the optional history log. Each transmission of
CTRL-E acts like the pressing of the ENTER key from the remote display, causing one of the 10
records to be transmitted. See “History Log Activation” section for additional details.
LOGIC MODULE STATUS LIGHTS & PUSH-BUTTONS
The logic module provides all the sequential logic, and safety startup and shutdown circuitry. On the
front of the module is the reset, scan and enter push-buttons, and status lights. This section describes
the their respective functions.
Limits
This LED illuminates when the operation limits are made. These limits are wired
in series to terminal J1-1. This input becomes energized to begin the burner
sequence. When in the test mode, this LED flashes (see “Pilot Test Mode”).
Air
This LED illuminates when the air switch is closed and power is thereby applied
to the air switch input. The Multi-Burner Control also checks this input for an air
switch short (see “Combustion Air Flow Check Terminal”).
Purge
This LED illuminates whenever the combustion blower is energized, including
the purge period and the main burner period of the sequence. It blinks on and off
while the purge is in process and remains constant when the purge process is
complete.
Burner On
This LED illuminates when the main gas valve is energized, permitting gas flow
to all the burners.
Fault
This LED illuminates when a system fault is detected and during the initial safe
start check (see “System Faults”).
Alarm
This LED illuminates when an alarm condition causes a system lockout
(see “System Lockout Conditions”).
Low Fire
This LED illuminates during the low fire period of the purge cycle.
High Fire
This LED illuminates during the high fire period of the purge cycle.
Scan
This push-button is for future use.
Enter
This push-button is used with the optional history logging.
LOGIC MODULE
RESET
LIMITS
AIR
PURGE
BURN ON
FAULT
ALARM
LOW FIRE
HIGH FIRE
SCAN
ENTER