Honeywell 900U02-0100 User And Installation Manual page 209

Number Possible Causes
of Red
Strobes
8 or 9 If 8 flashes, the S1
serial port is
reporting a
diagnostic.
If 9 flashes, the S2
serial port is
reporting a
diagnostic.
Possible causes
are:

If the port is
configured as a
Modbus or ELN
slave, the data
link layer is
reporting that at
least 75% of the
last characters
received have
had a failure
reported by the
UART or at least
75% of the last
messages
received have
been invalid.

If the port is
configured as a
Modbus Master,
at least 75% of
the last requests
to a particular
slave resulted in
no response or a
reply that failed
the data link
protocol.
2 The UART failed its
power-up tests
Revision 10 ControlEdge HC900 Process & Safety Controller User and Installation Manual
May 2019
Lead and/or Reserve
Controller Action(s)
ASYS and FSYS blocks' HW
1.
OK pins are turned off.
If configured as a Modbus
2.
master:
 ASYS and FSYS blocks'
Modbus Master Fail pins
are turned on.

Slave and read blocks
associated with the slaves
experiencing the failure
have their read pins frozen
to the last value read.

Slave blocks associated
with the slaves
experiencing the failure
have their BAD COMM
and NO SCAN pins turned
on.

IN SCAN STATUS is set to
NO for all slaves
experiencing the failure.

COMM STATUS is set to
BAD for all slaves
experiencing the failure.

The slaves with the data
link errors have a non-zero
data link error count.

The slaves experiencing
the failure are moved to the
background scan rate.
See above
User Action
Check baud rate
1.
Check connectors
2.
Check cable polarity
3.
Isolate cabling from electrical
4.
interference
If RS-232 to RS-485 converter
5.
is used, check its power,
switch/jumper settings, and
polarity.
If configured as a Modbus
6.
master, use the slave status
screens to determine which
slaves are experiencing the
problem. For those slaves
check:

Power

Connections

address

baud rate

parity

number of stop bits

for electrical interference

grounding

termination resistor (if at
end of link)
The diagnostic is cleared by
9.
clearing the port's statistics.
Replace CPU module
Honeywell OI HCDesigner/HC
Indication Utilities
Indication
 
195