Sram Test; Troubleshooting Auxiliary Control Boards (Ccb1And Ccb2) - McQuay MicroTech II Installation And Maintenance Manual

Bad CRC in Configuration Data Base. This is a fatal
error that will require replacement of the MCB. The configu-
ration database contains user and factory defined configura-
tion parameters including the device name, communication
parameters, and I/O setup and calibration data. After display-
ing the Configuration Flash CRC error during the MCB
Error Code Display period of the Main Control Board LED
Power-Up Sequence, the startup process continues. If main
code is run, the MCB will reboot resulting in endlessly
repeating the error code and reboot cycle. If boot code is run,
MCB will run with factory default values.

SRAM Test

Simply stated, the SRAM test checks each memory location
by writing values to them, reading the values back and com-
paring the read back values to the expected values. If a
SRAM error is detected in the low byte, the RAM Low Byte
failure is displayed during the MCB Error Code Display
period of the Main Control Board LED Power-Up Sequence.
The MCB is then reset by an external "watchdog" circuit and
the Main Control Board LED Power-Up Sequence begins
again. If a SRAM failure is detected in the high byte, the
RAM High Byte failure is displayed and the Serial Bus Port
LED is turned ON during the MCB Error Code Display
period of the Main Control Board LED Power-Up Sequence.
The MCB is then reset by an external "watchdog" circuit and
the Main Control Board LED Power-Up Sequence begins
again. If either the RAM Low Byte or the RAM High Byte
error occurs, MCB must be replaced.
Communication Port Tests
The various communication ports on the MCB are tested
during the Main Control Board LED Power-Up Sequence.
This feature allows the processor to verify the internal trans-
mit and receive data paths of MCB data communication
channels. Once in the test mode, proper operation of the var-
ious communication channels is verified by writing data to
the corresponding transmit buffer of the channel under test
and then reading the data back from the receive register. If
read data does not match write data, the MCB will display
the appropriate communication port error during the MCB
Error Code Display period of the Main Control Board LED
Power-Up Sequence and then continue startup and initializa-
tion. If any of the possible communication port errors occur,
MCB must be replaced to correct the problem.
Ethernet Register Test
After determining the existence of an optional Ethernet com-
munication card, the MCB will perform a series of
read/write tests on critical registers of the Ethernet processor.
If any of the register tests fail, an Ethernet port failure will be
displayed during the MCB Error Code Display period of the
Main Control Board LED Power-Up Sequence and then the
MCB will continue running startup and initialization. If the
Ethernet port error occurs, the Ethernet communication card
IM710
must be replaced to correct the problem. If the problem per-
sist, the Ethernet communication card must be replaced to
correct the problem. If the problem persists after replace-
ment of the Ethernet communication card, MCB is likely
defective. Refer also to the literature shipped with the Ether-
net communication card.
Troubleshooting Auxiliary Control Boards
(CCB1and CCB2)
This section outlines a typical process for troubleshooting
any of the auxiliary control boards that might be connected
to the MCB via the N2 communication bus interface.
Hardware Check
1. Verify the auxiliary control board has been wired and
terminated properly. Refer to the as-built unit wiring
schematics or refer to Figure 14 on page 34 (DAC units)
or Figure 15 on page 35 (SCC units).
2. Verify the N2 Communications Card on the auxiliary
control board is properly installed. Verify N2 Address
Switch on the N2 Communication Card is set to the cor-
rect address. Refer to Table 4 on page 11.
3. Verify that 24 VAC power is available and properly ter-
minated on the J1 terminal block on the auxiliary con-
trol board.
N2 Communication Card
Verify the N2 Communications Card is functioning properly.
The auxiliary control board N2 Communication Card is
physically the same part as the optional BACnet MSTP
Communication card that can be used to communicate with
the MCB. For a detailed description and troubleshooting
information regarding this communications card, refer to
installation and maintenance bulletin IM 704, MicroTech II
BACnet/MSTP Communications Module. Replace the N2
Communication Card if defective.
Note: The N2 Communications Card LED "DS1" will
blink whenever it detects N2 bus traffic. LED
"DS2" will blink whenever the auxiliary control
board is transmitting N2 messages.
Auxiliary Control Board Application Software
Verify that the application software functions as expected.
Refer to the applicable operation manual (Refer toTable 1 on
page 3). If the application does not appear to function cor-
rectly, the application code in the auxiliary control board can
be re-loaded using the MicroTech II Service Tool.
Verifying Operation
If the application software does not function as expected
then re-check the items above. If the above items are normal
and the problem persists, the auxiliary control board is likely
defective and should be replaced.
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