Table 9-Sequence And Status Hold Messages - Honeywell 7800 Series Manual

RM7838B
TROUBLESHOOTING
RM7838B SYSTEM DIAGNOSTICS
Troubleshooting control system equipment failures is
made easier with the RM7838B self-diagnostics and first-out
annunciation. In addition to an isolated spst alarm relay
(audible annunciation), the RM7838B provides visual an-
nunciation by displaying a fault code and fault or hold mes-
sage at the Keyboard Display Module 2 row by 20 character
VFD. The RM7838B provides 61 diagnostic messages for
troubleshooting the system.
Self-diagnostics of the RM7838B enables it to detect and
annunciate both external and internal system problems. In-
ternal faults and external faults such as interlock failures,
flame failures, and false flame signals are annunciated by the
RM7838B, which energizes the ALARM LED or the Key-
board Display Module VFD.
The VFD displays a sequence status message indicating:
STANDBY, PURGE, PILOT IGN, MAIN IGN and RUN.
The selectable messages also provide visual indication of
current status and historical status of the equipment such as:
Flame Signal, Total Cycles, Total Hours, Fault History, Diag-
nostic Information and Expanded Annunciator terminal sta-
tus (if used). With this information, most problems can be
diagnosed without extensive trial and error testing.
Table 9 provides the sequence and status hold messages.
Table 14 provides a summary of all RM7838B fault mes-
sages and fault codes. In addition, Diagnostic Information
and History Data are available to assist in troubleshooting the
RM7838B, see Table 10.
The RM7838B provides diagnostic information to aid the
service mechanic in obtaining information when trouble-
shooting the system, see Tables 9, 10, 11, 12. Information
available in the Diagnostic Information includes Device
Type, Device Suffix, Software Revision, Manufacturing
Code, Flame Amplifier Type, Flame Failure Response Time,
Selectable Jumper Configuration Status, Run/Test Switch
Status and Terminal Status.
NOTE: Normal sequences are in BOLD type, while abnormal sequences are not in bold type.
Sequence
INITIATE mm:ss
INITIATE HOLD: AC
(AC Frequency/Noise)
INITIATE HOLD: AC
(AC Line Dropout)
65-0120—1
TABLE 9—SEQUENCE AND STATUS HOLD MESSAGES.
Message
The VFD indicates the burner status, INITIATE, which is a stabilization period
for the RM7838B to check for any fluctuations in AC line voltage inputs or
control input on powerup or during normal operation. The timing of the
INITIATE period is ten seconds before entering STANDBY.
The VFD indicates the burner status, INITIATE, and that it is waiting for excess
line noise to clear up. The burner sequence will not advance into STANDBY
until the excess line noise, which prevents sufficient reading of the line voltage
inputs, ceases or a line frequency error is corrected (perhaps caused by using a
60 Hz device on a 50 Hz line, or vice versa).
The VFD indicates the burner status, INITIATE, and that AC line power has
momentarily dropped out. The burner sequence will not advance into STANDBY
until the AC line voltage has stabilized throughout the INITIATE period.
Troubleshooting
DIAGNOSTIC INFORMATION INDEX
The RM7838B monitors input/output terminals and can
display the status of the terminal at the VFD (example: Pilot
Valve T8 ON<). See Table 11 for a complete terminal
description and number. The display will show the actual
status of the terminal. If voltage is detected at the terminal,
ON is displayed, but if no voltage is detected at the terminal,
OFF is displayed, see Table 11.
HISTORICAL INFORMATION INDEX
The RM7838B has nonvolatile memory that allows the
Relay Module to retain historical information for the six most
recent lockouts. Each of the six lockout files retains the cycle
when the fault occurred, the hour of operation when the fault
occurred, a fault code, a fault message and burner status
when the fault occurred, see Table 10.
SERVICE NOTE: If the Keyboard Display Module VFD is
scrambled, remove and reinstall the Keyboard Display
Module, and reset the RM7838B Relay Module.
SERVICE NOTE: Reset RM7838B by pressing the reset
pushbutton on the RM7838B, or pressing a remote reset
pushbutton wired through the Keyboard Display Module,
DATA CONTROLBUS MODULE™, or Remote Reset
Module. A power-up reset will cause an electrical reset of
the RM7838B but will not reset a lockout condition.
SERVICE NOTE: Use the access slots on the sides of the
Q7800A,B to check terminal voltage.
SERVICE NOTE: Maximum ambient operating tem-
perature of a C7012E,F, Series 1 through 6, will be reduced
to 125° F because of the duty cycle operation of the
RM7838B Relay Module.
42
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