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Unit Controls
HISTORY PRINTOUT
Pressing the PRINT key and then the HISTORY key al-
lows the operator to obtain a printout of information relat-
ing to the last 6 Safety Shutdowns which occurred. The
information is stored at the instant of the fault, regard-
less of whether the fault caused a lockout to occur. The
information is also not affected by power failures (long
term internal memory battery backup is built into the
circuit board) or manual resetting of a fault lock-out.
When the HISTORY key is pressed, a printout is trans-
mitted of all system operating conditions which were
stored at the "instant the fault occurred" for each of the
6 Safety Shutdowns buffers. The printout will begin with
the most recent fault which occurred. The most recent
fault will always be stored as Safety Shutdown No. 1.
Identically formatted fault information will then be printed
for the remaining safety shutdowns.
Information contained in the Safety Shutdown buffers is
very important when attempting to troubleshoot a sys-
tem problem. This data reflects the system conditions
at the instant the fault occurred and often reveals other
system conditions which actually caused the safety
threshold to be exceeded.
The history printout is similar to the operational data
printout shown in the previous section. The differences
are in the header and the schedule information. The daily
schedule is not printed in a history print.
One example history buffer printout is shown. The data
part of the printout will be exactly the same as the op-
erational data print, so it is not repeated here. The differ-
ence is that the Daily Schedule is not printed in the his-
tory print and the header will be as shown.
108
YORK INTERNATIONAL CORPORATION
MILLENNIUM CONDENSING UNIT
SAFETY SHUTDOWN NUMBER 1
SHUTDOWN @ 3:56PM
SYS 1
HIGH DSCH PRESS SHUTDOWN
SYS 2
HISTORY DISPLAYS
The HISTORY key gives the user access to many unit
and system operating parameters at the time of a unit or
system safety shutdown. When the HISTORY key is
pressed the following message is displayed.
D I S P L A Y
S A F E T Y
D O W N
N O .
While this message is displayed, the UP or DOWN ar-
row keys can be used to select any of the six history
buffers. Buffer number 1 is the most recent, and buffer
number 6 is the oldest safety shutdown that was saved.
After selecting the shutdown number, pressing the EN-
TER key displays the following message, which shows
when the shutdown occurred.
S H U T
D O W N
1 1 : 2 3
P M
29 SEP 97
NO FAULTS
S H U T-
1
( 1 T O 6 )
O C C U R R E D
2 9
M A Y
9 8
YORK INTERNATIONAL
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