QUANTUM
™
LX EVAPORATOR CONTROL PANEL
COMMUNICATIONS SETUP
090.610-CS (MAY 2016)
Page 113
Q4 SERIAL COMMUNICATIONS HARDWARE
Q4 GENERAL DESCRIPTION
Serial communications to and from the Q4 can use
RS-232, RS-422 and/or RS-485 hardware protocol.
These three hardware protocols can be connected
via Com-1 and Com-2 for RS-422/485, and Com-2
for RS-232. The reason that Com-2 can be either
RS-232 or RS-422/485 will be explained in the sec-
tion entitled Com-1 and Com-2 Description.
The Com-1 and Com-2 serial communications
portion of the Q4 controller consists of a daughter
board, mounted to the main controller. In addition
to external forms of serial communication (to be
discussed shortly), the keypad also connects here.
Com-3 is another serial port (RS-485) that is dedi-
cated to providing communications to the DIgital
and Analog boards. The location of Com-3 is on
the main processor board and will be explained in
the section entitled Com-3 Description.
RS-232 signals cannot be connected directly to ei-
ther an RS-422 or RS-485 device. These signals
must rst be conditioned (converted). See the
section entitled Converting an RS-232 Signal to
RS-422/485 for details.
C
ommunications Ports on the Q4 Daughter
Board
Com-3
RS-485
Com-1
RS-422/485
TB2
Com-2
Com-2
RS-232
COM-1 AND COM-2 DESCRIPTION
The board pictured in the previous column actually
has three serial communications ports (labeled as
TB1, TB2 and TB3). TB1 is known as Com-1, and is re-
served solely for RS-422/485 communications. It can
be used for external communications to the outside
world.
TB2 is known as Com-2. However, TB3 is also known
as Com-2. The difference here is that TB2 is for RS-
422/485 whereas TB3 is for RS-232. TB2 can be used
in the same manner as TB1.
When TB2 (Com-2) is setup to be used for RS-422/485,
then TB3 cannot be used for RS-232, and vice-versa.
The reason for this is that there is a jumper (LK11) that
needs to be properly set that will tell the controller
which of the two ports will be used (either TB2 as RS-
422/285 OR TB3 as RS-232).
RS-422/RS-485 signals cannot be connected directly
to an RS-232 device. These signals must rst be con-
ditioned (converted). See the section entitled Con-
verting an RS-232 Signal to RS-422/485 for details.
COM-3 DESCRIPTION
Com-3 (PL6) is used for RS-232 hardware protocol
only, and can be used in addition to any of the other
communications ports that may be being used. So it
is possible to have two RS-232 ports active (Com-2
AND Com-3) at the same time, as well as Com-1 for
RS-422/485.
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