Troubleshooting Keypad/Display - McQuay MicroTech II Installation And Maintenance Manual

Troubleshooting Keypad/Display

Keypad/Display Power Up Initialization
When the keypad/display is connected to the MCB and
power is applied, the firmware in the keypad/display will run
a diagnostic test of its static RAM (SRAM) and will also
check the micro controller ROM for proper checksum. After
these tests are completed, the keypad/display will respond to
a poll of its address by the MCB with an acknowledge mes-
sage to the MCB. This will cause the controller to start
downloading display information to the keypad/display. The
keypad will be locked out until the tests and the download is
complete. Note: The keypad/display address is defined by a
four-position dip switch block on the right side of the device.
For this application, all four of these switches should be in
the UP position, which defines address 32.
When the keypad/display is connected to the MCB and
power is applied, the display will have the backlight and the
red Alarm LED turned on. The backlight will remain on until
it times out (15 minutes after a key press or after power up).
During the next 5 seconds, the LCD will count down from 9
to 0 in all 80 character locations. After the countdown is
complete, the Alarm LED will turn off and the display will
appear as follows:
Version xxx
Address yy
Status zz zzzz
Startup aaaa bbbb ccc
Where:
46
xxx = The version of firmware in the keypad/display
yy = The keypad/display address 32
zzzz = OK normally or NO COMM if the MCB is not com-
municating with the keypad/display
aaaa = OK normally or IRAM of internal RAM test failed
bbbb = OK normally or XRAM if external RAM test failed
ccc = OK normally or ROM if ROM checksum does not
match stored checksum
When the MCB finishes downloading to the keypad/display
it sends a "download complete" message to the keypad/dis-
play. When this message is received by the keypad/display,
the LCD will show the "main" self-contained application
menu screen.
Note: A NO COMM indication on the Status line during
the initialization period does not necessarily indi-
cate a problem. A communication problem is indi-
cated if the LCD remains indefinitely showing the
initialization display screen as shown above with
the Status line indicating NO COMM. In other
words, the LCD will not proceed to show the
"main" application menu screen.
If aaaa= IRAM, bbbb= XRAM and/or ccc= ROM, the key-
pad/display must be replaced.
Note: The keypad/display may be connected to the MCB
while power is on. The normal elapsed time for the
"main" self-contained menu screen to appear in the
LCD upon initializing is approximately 60 seconds.
IM710