231
FORM 160.54-M1
ISSUE DATE: 10/25/2019
JOHNSON CONTROLS
JCI COMPANY CONFIDENTIAL
27
Beginning August 2009, new chillers equipped for Hot
gas bypass, Heat Recovery and/or Head Pressure Con-
trol options will be equipped with Input/Output Board
031-02895-000. It provides both Analog and Digital
Input/Output capability to the microboard from ex-
ternal devices.
is a top level
through Figure 90 on page 235
show details of the
I/O circuits and should be referred to while reading the
following description of the board operation.
is a board layout showing component
identification.
The board is manufactured with either a -000 or -001
part number suffix. The -000 board is only populated
with the components required for options requiring
small additional I/O counts. The -001 board is for fu-
ture use.
This board operates from +12 VDC (TP3) and +24 VDC
(TP4) power supply voltages. The +12 VDC applied to
the +5 VDC regulator produces a +5 VDC regulated
output (TP2), which causes the POWER LED (CR3) to
illuminate. These voltages are referenced to GND (TP1).
Power fail circuits detect low DC voltage and put the
processor into a reset state as long as the voltage is
below a threshold. This prevents the processor from
processing data while the DC Voltage is below the
minimum required for stable circuit operation. The low
voltage reset thresholds are:
• +5 VDC supply @ 4.41 VDC-4.87 VDC
• +12 VDC supply @ 9.6 VDC-11.2 VDC
When the I/O Board is operating, the STATUS LED
(CR8) flashes at a regular interval (1/sec) indicating
that the board is functional.
This board communicates with the microboard COM
3 serial port (J12) using Modbus Protocol RS-485 se-
rial communications. When a read/write request is sent
from the microboard, the microboard’s TX3 (CR15)
LED illuminates. When that request is received at the
I/O Board, the I/O Board’s RX (CR4) LED illuminates.
When the I/O Board responds, the I/O Board’s TX
(CR5) LED illuminates. When the response is received
at the microboard, the microboard’s RX3 (CR16) il-
luminates.
SECTION 27 - LARGE TONNAGE CHILLER (LTC) I/O BOARD
031-02895-000/001
Each read/write request from the microboard contains
a Modbus Net address. In order for the I/O Board to
respond to the microboard’s requests, the Modbus Net
address of the I/O Board must match the one sent from
the microboard. The Modbus Net address of the I/O
Board is set with 4 position DIP switch SW1, labeled
NET ADDRESS. This should be set to “1” by setting
SW1-1 to ON and the other segments to OFF.
The operating program is stored in the processor. The
program is downloaded into the processor through the
J1 programming port at the time of board manufacture.
Service replacement boards are provided preloaded
with the proper software. It is not necessary to field
load software into the board.
This board is only compatible with Microboard 031-02430-
000/-001 equipped with software version C.OPT.01.21.307
(or later). It cannot be used with Microboard 031-01730-
000 or any previous software versions.
See the following sections of this manual for a descrip-
tion of how this board is interfaced for these applica-
tions:
•
Hot gas bypass
•
Heat Recovery
•
Head Pressure Control
Important!
These are not general pur-
pose I/O points available for field use.
Unless specifically listed in above refer
-
enced sections of this manual, the I/O
point cannot be used.
DIGITAL INPUTS
120 VAC Digital inputs
These inputs accept a 120 VAC input.
is a detail of this input and is representa-
tive of all of these inputs. Each input is applied to the
respective (+) and (-) input. Each input is applied to
an optocoupler circuit that converts the AC voltage to
a DC voltage. Each input has an LED associated with
it. The respective LED illuminates when the 120 VAC
input is present. Otherwise, it is extinguished. The -000
board is component populated for 2 inputs. The -001
board is populated for 6 inputs.