JOHNSON CONTROLS
251
SECTION 8 - MICROPANEL
FORM 201.23-NM2 
ISSUE DATE: 09/25/2020
8
HISTORY KEY
LD10605
HISTORY 
KEY
History Key Operation
The HISTORY key provides the user access to many 
unit and system operating parameters captured at the 
instant a unit or system safety (fault) shutdown occurs. 
The history buffer will also capture system data at the 
time of normal shutdowns such as cycling shutdowns.  
When the HISTORY key is pressed the following 
screen is displayed:
HISTORY          CHOOSE HISTORY TYPE
◄ ► XXXXXXXXXXXXXXXXXXXXXXXXXXXX
The  ◄ and ► (ARROW) keys allow choosing be-
tween NORMAL SHUTDOWNS and FAULT SHUT-
DOWNS. “Fault” shutdowns provide information on 
safety shutdowns, while “Normal” shutdowns provide 
chiller cycling information on temperature (demand), 
cycling, remote, system switch, etc., shutdowns that 
are non-safety related shutdowns. Once the selection 
is made, the  (ENTER) key must be pressed to enter 
the selection.
Normal Shutdowns History
If the NORMAL SHUTDOWNS History is selected, 
the following screen will be displayed:
NORM  HIST  XX   18-JUN-20004  10:34:58 AM
YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY
XX is the normal shutdown number. The display will 
provide date and time of the shutdown and the reason 
for the cycling shutdown (YYY….). 
The operator can view any of the stored 20 single dis-
play normal shutdown history buffers. History buffer 
number 1 provides the most recent shutdown informa-
tion and buffer number 20 is the oldest safety shutdown 
information saved. The ◄ and ► (ARROW) keys allow 
scrolling between each of the history buffers. The ► 
(ARROW) key scrolls to the next normal history shut-
down and the ◄ (ARROW) key scrolls to the previous 
normal history shutdown.
The following display will typically be displayed on a 
normal shutdown due to shutdown on lack of cooling 
demand.
NORM  HIST  XX   18-JUN-20004  10:34:58 AM
SYS  X  COOLING  DEMAND  SHUTDOWN