Honeywell W7750A Manual

A SERVICE OF

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EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER

74-2958—150

NOTE: The node can be reset b

y

switchin

g

the node to

MANUAL and then to the normal operatin

g

mode

(

see Fan Operation in Appendix B

)

.

Also, the Excel 10 variables,

AlarmLogX

where

X

is 1 throu

g

h

5, that store the last five alarms to occur in the controller, are

available. These points can be viewed throu

g

h XBS or

E-Vision.

Certain alarm conditions are suppressed conditionall

y

as

follows:

Broadcasting the Service Message

The Service Messa

g

e allows a device on the L

ON

W

ORKS

Bus

to be positivel

y

identified. The Service Messa

g

e contains the

controller ID number and, therefore, can be used to confirm

the ph

y

sical location of a particular Excel 10 in a buildin

g

.

There are three methods of broadcastin

g

the Service

Messa

g

e from an Excel 10 W7750 Controller. One uses a

hardware service pin button on the side of the controller

(

see

Fi

g

. 41

)

. The second uses the wall module pushbutton

(

see

Fi

g

. 43 and 44

)

. B

y

pressin

g

the wall module pushbutton for

more than four seconds, the controller sends out the Service

Messa

g

e. The third involves usin

g

the PC Confi

g

uration tool,

as follows.

When an

Assign ID

command is issued from the

commissionin

g

tool, the node

g

oes into the

SERVICE_MESSAGE mode for five minutes. In the

SERVICE_MESSAGE mode, pressin

g

the Occupanc

y

Override button on the remote wall module

(

refer to Fi

g

. 43

and 44 for override button location

)

causes the Service

Messa

g

e to be broadcast on the network. All other functions

are normal in the SERVICE_MESSAGE mode. Even if an

Excel 10 W7750 Controller does not have an Override button

connected, it can broadcast the Service Messa

g

e on the

network b

y

temporaril

y

shortin

g

the Controller B

y

pass Input

terminal to the Sensor Ground terminal on the W7750A,B,C

(

short terminals 3 and 5

)

.

The commissionin

g

tool is used to perform the ID Assi

g

nment

task

(

see the E-Vision User’s Guide, form 74-2588

)

.

Fig. 41. Location of the Service Pin Button.

W7750 Controller Status LED

The LED on the front and center of a W7750 Controller

provides a visual indication of the status of the device. See

Fi

g

. 42. When the W7750 receives power, the LED should

appear in one of the followin

g

allowable states:

1.

Off—no power to the processor.

2.

Continuousl

y

On—processor is in initialized state.

3.

Slow Blink—controllin

g

, normal state.

4.

Fast Blink—when the Excel 10 has an alarm condition.

LOSS_OF_AIR_FLOW 6 The Fan Status DI indicates that there is no air flow when the node is

commandin

g

the fan to run. The control is shut down and disabled until power is

c

y

cled or the node is reset. See NOTE below. The alarm is not issued until

FanFailTime seconds have elapsed since the loss-of-flow condition was first

reported

DIRTY_FILTER 7 The pressure drop across the filter exceeds the limit and the filter re

q

uires

maintenance. The control runs normall

y

.

SMOKE_ALARM 8 The smoke detector has detected smoke and the node has entered an

emer

g

enc

y

state.

IAQ_OVERRIDE 9 The indoor air

q

ualit

y

sensor has detected that the indoor air

q

ualit

y

is less than

the desired standard and additional outdoor air is bein

g

brou

g

ht into the

conditioned space.

LOW_LIM_ECON_CLOSE 10 The economizer has to close be

y

ond the minimum position to prevent the

dischar

g

e air temperature from

g

oin

g

below the dischar

g

e temperature low limit.

Table 12. Excel 10 Alarms. (Continued)

Name of alarm or error bit

Alarm type

number Meaning of alarm code or error bit

M10094

SERVICE

PIN

BUTTON