Troubleshooting; Communicating Through Modbus - Honeywell U2 User Manual

Auto Filter
Routine that automatically determines the optimum filter for
the SSUV and IR sensors. This routine should only be done
after the AUTO GAIN routine.
NOTE: While using the Auto Gain and Auto Filter modes,
the system will be adjusting to the firing condi-
tions at the time of implementation. This condi-
tion should be carefully selected to ensure
discrimination through complete load changes
from minimum to maximum and from cold
burner/boiler startup to hot burner/boiler startup.
Default
Tapping will access the file default and factory default sub
menus.
File Default
Changes the settings of the current file being adjusted (see
FILE menu).
Factory Default
Changes all settings to factory default settings.
Communications, security, and all file settings will have to be
reset so only initiate factory defaults when absolutely
necessary.

TROUBLESHOOTING

"9999" on Display
"9999" on the U2 display can indicate saturation of the UVSS
and/or IR sensor in addition to the PANEL Time Out sub-menu
being accessed. First check to see if the PANEL Time Out
sub-menu has been accessed and exit the menu as described
in the Panel section of this document. If the problem still
persists, then sensor saturation is likely. Decrease the gain for
UVSS and/or IR sensor to 0, then gradually increase the gain
level(s) to a suitable level to prevent saturation. In rare cases,
an orifice disk may be required. Refer to the ACCESSORIES
section of this document for part numbers.
If saturation of the IR or SSUV sensor persists for greater than
1 second, the flame Relay will open, and the U2 will lock out
with an error code: code 1 for SSUV saturation and code 8 for
IR saturation. When a lockout occurs, the U2 must be reset to
continue normal operation. This is accomplished by pressing
the enter key twice at the front panel.
Lockout Message
If a lockout message appears on the screen, the user has
attempted to access the U2 menus while the PANEL Lock
feature is enabled. The Lock feature requires a special 4-digit
code for access and modification, which is available from the
factory. If the password is forgotten or lost, the user must
contact the factory for assistance with unlocking the panel.
Refer to the Panel section of this manual and/or contact the
factory for assistance.
U2 COMBINATION VIEWING HEAD AND SIGNAL PROCESSORS
"Bad" Message
If the display shows "Bad" upon entering the access code for
the PANEL Lock feature, it means the access code that was
just entered is incorrect. Refer to the Panel section of this
manual for further details.
NOTE: Refer to "Grounding and Shielding" on page 3 for
further troubleshooting help in regards to proper
grounding and shielding techniques.
COMMUNICATING THROUGH
MODBUS
Modbus RTU communication protocol allows the U2 to
communicate with any process controllers or human-Interface
host computers that support this protocol. When
communicating through Modbus, use the following register
map to access and control the U2:
— 9600 baud (default)
— 8 data bits
— no parity (default)
— 1 stop bit
Baud, parity, and address are all changeable via the U2
interface in the "Comms" menu. The address is set to 0 by
default and must be changed in order to communicate with the
unit. When communicating with more than one unit ensure
that no two units share the same address.
A graphical user interface is available for remote configuration
and monitoring through Modbus called Flame Tools. Refer to
Table 4 and 5 for the Modbus registers map.
Comms
Tapping COMMS on the U2 menu will access the
communications sub menus including address, baud, parity,
IRDA, RS485, and current output.
Address
Address for modbus communication (0-247). When
communicating with more than one unit ensure that no two
units share the same address. The default address is 0 so it
must be changed before modbus communication can take
place. For applications where large quantities of U2 are used,
it is recommended to start with address 11 for burner #1, 21
for burner #2 and so on. Refer to Fig. 3. Doing so will help
alleviate potential communication issues when adding new or
replacing existing U2 models, which have zero (0) as the
default address. Two units with a 0 address could seize
communications.
Baud
Speed of modbus communications (2400, 4800, 9600, 19200,
38400, 57600, or 115200). The default baud is 9600.
Parity
Modbus checking method (NONE, ODD, or EVEN). The
default parity is NONE.
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