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MODEL PCA090480WH
CHAPTER 3
TROUBLESHOOTING
Section 6: Troubleshooting Direct Digital Controller (DDC)
March 2013
3-6
Proprietary/Confidential
Page
93
© 2013 Twist, Inc.
Troubleshooting the ALC is divided into three tasks. First, check the operation of the
ALC itself to ensure proper operation. Next, check the inputs to be sure they are
responding correctly. Lastly, test the outputs to be sure all wiring and safety devices
are in proper order.
1.
Determining if ALC is Operating Properly
Check to be sure that 24 VAC power is applied properly. This can be
determined this quite easily by looking at the ALC in the control panel. If any
LED’s are lit or blinking, the ALC is receiving power. If the power condition is
still in question, check that the power switch is in the ON position then check
the power connection of the ALC from the terminal labeled 24VAC to Gnd
using a digital multi meter (DMM). This is the AC power supply for the ALC and
should be within 10% of 24 VAC. If proper voltage is applied but the above
conditions do not occur either the software is not loaded correctly, or the ALC
is possibly defective.
A red LED labeled POWER on the right hand side of the ALC will show
whenever power is being provided to the ALC.
NOTE:
The I/O Flex 6126 is protected by internal solid state Polyswitches on
the incoming power and the network connections. These
Polyswitches are not replaceable and will reset themselves if the
condition that caused the fault returns to normal.
There is a run LED and error LED. These LED indicates the condition of the
module.
Run LED
Error LED
Condition
2 flashes / second
Off
Normal
2 flashes / second
2 flashes alternating
Five minute auto delay
after system error.
2 flashes / second
2 flashes in sync,
Module is configured for a
then pause.
different baud rate than the
rest of the network segment.
2 flashes / second
3 flashes, then off
Module has been formatted
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