QUANTUM
™
LX EVAPORATOR CONTROL PANEL
COMMUNICATIONS SETUP
090.610-CS (MAY 2016)
Page 118
TROUBLESHOOTING RS-485
Com-1 (TB1)
Notice that in the gure entitled RS-485 Com-1
(TB1) Connector, Jumpers & LED Location, there
are seven jumpers associated with TB1. Refer to
the table entitled RS-485 (TB1) Board Jumpers for
the function of each of these jumpers. Note: LK16
must be set to position B. Notice also the two LED
indicators that are pointed out in the gure. D3
LED will ash each time that the Q4 transmits (TX)
data. D2 LED will ash each time that data is re-
ceived (RX).
If communications with the Q4 cannot be estab-
lished using TB1, then note the status of these two
LED’s (D2 and D3). If D2 is constantly lit, it may
indicate an external wiring issue (TX and RX pos-
sibly swapped). If D2 never ashes, then the LX is
not receiving any data. If D2 ashes each time a
data bit is received, but D3 never ashes, this may
indicate that the LX has received a data command,
but that the protocol package is not properly for-
matted, and the LX cannot respond.
On the Communications Setup screen, verify that
the proper Panel ID, Baud rate, data bits, and pro-
tocol matches that of the initiating device.
Com-2 (TB2)
Notice that in the gure entitled RS-485 Com-2
(TB2) Connector, Jumpers & LED Location, there
are seven jumpers associated with TB2. Refer to
table entitled RS-485 (TB2) Board Jumpers for
the function of each of these jumpers. Note: LK11
must be set to position B, and LK17 must be set to
position B. Notice also the two LED indicators that
are pointed out in the gure. D1 LED will ash each
time that the Q4 transmits (TX) data. D6 LED will
ash each time that data is received (RX).
If communications with the Q4 cannot be estab-
lished using TB2, then note the status of these two
LED’s (D1 and D6). If D1 is constantly lit, it may
indicate an external wiring issue (TX and RX pos-
sibly swapped). If D6 never ashes, then the LX is
not receiving any data. If D6 does ash each time a
data bit is received, but D1 never ashes, this may
indicate that the LX has received a data command,
but that the protocol package is not properly for-
matted, and the LX cannot respond.
On the Communications Setup screen, verify that
the proper Panel ID, Baud rate, data bits, and pro-
tocol matches that of the initiating device.
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