Table of Contents
Advertisement
090.040-M (MAR 12)
Page 26
INFORMATION
The information that follows in this section can help
locate problems that can occur with Digital Input and
Output circuit boards.
DIGITAL BOARD DESCRIPTION
The Digital board is a small microprocessor board and
is programmed to control discrete outputs, or accept
discrete inputs, from external electrical devices. Each
Digital board has the capability of 24 independent
channels or I/O (Input/Output). Each channel that is
used needs a module plugged into it. A yellow mod-
ule indicates that it is used for Inputs. A black mod-
ule is used for Outputs. The standard Quantum™ HD
compressor control can have up to two Digital boards
(depending on options).
COMMUNICATIONS LED'S
The Q5 board is in constant communication with all
Digital (and Analog) Boards. You will notice on each
Digital and Analog board, there are a pair of LED's
labeled as RX and TX. These letters represent Re-
ceive (RX) and Transmit (TX). These LED's should be
fl ashing at a high rate during normal operation. This
indicates that the Q5 board, and the Digital board are
properly communicating with each other.
•
Reference the JUMPER AND DIPSWITCH
SETTINGS section later in this manual. This
section contains the dipswitch settings for
addressing the Digital I/O boards. When
these switches are properly set, the main
board is able to serially communicate with
each I/O board and provide control signals
and data exchange. If these switches are not
properly set, the result will be lost or failed
communications, or the wrong outputs be-
ing energized, or the wrong inputs being re-
ceived.
CONNECTIONS TO THE QUANTUM™
As stated earlier, the Quantum™ HD standard com-
pressor control system utilizes up to two Digital, and
two Analog boards. To connect these boards togeth-
er so that the Quantum™ HD can control them, they
must be interconnected with a wiring harness that
provides all of the necessary D.C. voltage require-
ments, as well as the communications capabilities.
The Digital boards only require the +5 Vdc voltage
and the Return (or common) for logic power. The
communications signals (RX & TX) are required by
all boards.
A harness distributes power and communications
from the terminal blocks to the various logic boards.
The harness splits into two branches, each ends with
QUANTUM™ HD COMPRESSOR CONTROL PANEL
MAINTENANCE
DIGITAL BOARD
two 16 pin connectors. The branch that supplies pow-
er and communications to the Digital board(s) utilizes
red and black wires for +5Vdc power and Common,
and white/black and white/red wires for serial com-
munications.
LOGIC VOLTAGE (POWER) LED
Located on the Digital Board is a Power LED. This
LED will be illuminated as long as the Control Power
switch is ON, and the proper voltage is present at
the power supply. The power supply generates the +5
Vdc voltage and passes it on through the Power-I/O
harness. This LED does not indicate however that the
proper voltage is necessarily present at the board,
only that the voltage is enough to energize the volt-
age sensing circuitry. If a voltage related problem is
suspected with regard to a Digital Board, the only
way to actually determine this is to read the volt-
age on a Digital Voltage Meter (DVM). This may be
accomplished by locating the white power / com-
munications connector on the board. Notice that the
Digital Board has one of these connectors on both
ends of the board. The associated power / communi-
cations harness will only be plugged into one of these
connectors. Take the red (positive) probe of the DVM
and carefully insert the end into the "+5V" lead, and
the black (negative) probe end into the "RET" (Return
or Common) lead, as shown below:
Red
+5V
Black
RET
Set the DVM to read DC, and set the proper range.
The voltage reading must read a minimum of +5.0
Vdc. The Power-I/O harness will have an associated
voltage drop at each board connection. As an exam-
ple, if you are reading 5.20 Vdc at the fi rst I/O board
in the daisy chain, the voltage at the subsequent con-
nections for the remaining boards may be lower. The
voltage will need to be corrected for proper opera-
tion of the system. The cause for a low voltage read-
ing could be:
•
The power supply may need adjustment
(see the section on power supplies).
•
The Power-I/O communications harness has
a problem (a new harness may be needed).
•
A problem may exist with one of the I/O
boards (Digital or Analog).
•
If the power LED is not lighted, check the
cable for proper connectivity. Note: Each
board provides the necessary connections
Advertisement
Table of Contents
Troubleshooting
