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SECTION 3 - MICROBOARD 031-01730-000
FORM 160.54-M1
ISSUE DATE: 10/25/2019
JOHNSON CONTROLS
JCI COMPANY CONFIDENTIAL
3
Style B Solid State Starter or Variable Speed
Drive Interface
If equipped with either of these drives, the drive is in-
terfaced to the microboard via the Opto-Coupled COM
5 serial data port (J15). The serial data is represented
by +5 VDC and 0 VDC logic levels. The TX data to the
drive is located at J15-1 and J15-2 is RX data from the
drive. See
SECTION 13 - SOLID STATE STARTERS
and
SECTION 14 - ADAPTIVE CAPACITY CONTROL
for details of this interface.
Printer Interface
An optional Printer can be connected to COM1 RS-
232 serial data port (J2). TX data to the printer is lo-
cated at J2-4 and J2-2 is the DSR (Data Set Ready or
busy) signal from the printer. Signal levels are standard
RS-232. The microboard sends data to the printer at
the selected baud rate until the printer buffer becomes
full, whereupon the printer asserts its Busy signal. The
microboard suspends data transmission until the print-
er can accept more data. Each printer must be setup/
configured to operate properly with the microboard.
The Baud, Data Bits, Parity and Stop Bits must be pro-
grammed on the COMMS Screen. Other printer setup
is performed on the Printer Screen. Refer to
OptiView
Control Panel – Operation (Form 160.54-O1)
for de-
tails of available printers and printer setup instructions.
E-Link Gateway Interface
An optional E-Link Gateway printed circuit board can
be connected to the COM 4B RS-232 serial data port
(J2). J2-7 is TX data to the E-Link Gateway. The RX
data is located at J2-6. Signal levels are standard RS-
232. The E-Link Gateway polls system pressures, tem-
peratures and status from the microboard. It holds it
for retrieval by third-party devices. See
of this manual.
Digital inputs
The I/O Board converts the 115 VAC inputs to logic
level inputs for the microboard at J19. A 115 VAC input
to the I/O Board is converted to a logic low (less than 1
VDC). A 0 VAC input to the I/O Board is converted to
a logic high (more than 4 VDC). See
of this manual for details of the I/O Board.
Digital Outputs
The microboard controls 115 VAC relays and solenoids
via the I/O Board (via J19). The I/O Board contains
+12 VDC relays that isolate the microboard low volt-
age circuits from the 115 VAC device coils. Solid state
switching devices are used to control the relays. The
microboard energizes the +12 VDC relays by applying
a ground to the coil input. They are de-energized by
opening the ground path. The contacts of these relays
switch 115 VAC to system relays and solenoids. The
outputs that control the chilled liquid pump and com-
pressor motor starter have anti-chatter (anti-recycle)
timers associated with them. The output that controls
relay K0 is not allowed to change at a rate greater than
once every 10 seconds. The output that controls relay
K13 is not allowed to change at a rate greater than once
every 20 seconds.
The microboard controls actuator motors via triacs on
the I/O board. Each actuator has an open winding and
a close winding. Current flowing through a winding
causes the actuator to rotate in the respective direc-
tion. Each winding is controlled by a triac. The triac is
turned on to allow current to flow through a winding.
The microboard turns on the triac by applying a logic
low (less than 1 VDC) to the triac driver on the I/O
board. It turns it OFF by applying a logic high (more
than 4 VDC). See
of this
manual for details of the I/O Board.
Analog Inputs
System pressures, in the form of analog DC voltages,
are input from Pressure Transducers. See
of this manual. Formu-
las and graphs are included to calculate the expected
transducer output voltage for a given pressure input.
System temperatures, in the form of analog DC volt-
ages, are input from thermistors. See
of this manual.
Included are tables to convert the expected output volt-
age for any temperature applied to the thermistor.