6
OM 200MICRO
Component Description
Microprocessor Control Board (MCB1)
The Model 280 Microprocessor Control Board
contains the electronic hardware and software
required to monitor and control the unit. It receives
input from the ADI Board and sends commands to
the Output Board to maintain the unit's optimum
operating mode for the current conditions. Status
lights are mounted on the control board to indicate
the operating condition of the microprocessor.
Pre-Start Checkout
Hexadecimal Switches
For proper chiller operation, each MicroTech
controller must have a unique network address. The
controller’s hex switch settings define it’s location in a network as well as it’s unit type. For a stand-
alone chiller, the Hi and Lo switches should be set to 0 and 1 respectively. After changing a hex
switch setting, the controller’s power must be cycled by opening, and then closing, the panel circuit
breaker.
Note
: The chiller should be in an “Off” mode before resetting the hex switch positions.
Powering the Control Panel
There are three status LED’s located on the model 280 controller which will indicate the
microprocessor’s operating condition. When power is first applied to the control panel, the red
reset
LED will illuminate for approximately 3 seconds. During this time, the microprocessor is checking the
control software and performing internal hardware tests. When these tests are complete the
reset
LED
will turn off and the green
running
LED will illuminate indicating the controller’s circuitry and software
are operating correctly. The amber
output 0 active
LED is associated with the external alarm output.
This LED may or may not be illuminated at this time based on the setpoints under menu 36.
Figure 3, Status LEDs
If the
reset
LED stays on or the
running
LED fails to illuminate, disconnect the controller power by
opening circuit breaker CB-1 and re-check the field wiring. Observe the controller’s LED’s while re-
connecting power by closing CB-1. If the green running LED still does not turn on, a hardware failure
exists or the control software is corrupted. Downloading new control software or replacing the 280
controller should correct the problem.
Figure 2, Model 280 Microprocessor
Control Board
green
red
amber
RUNNING
RESET
ACTIVE
CPU
STATUS
OUTPUT 0
