6
e. Check Alarm/Service light. If illuminated, check Interface
panel.
1) If SERVICE DRYER appears, scheduled maintenance
time has elapsed (HRS TO SERVICE is 0). Perform
needed service and reset service interval (see B.4.).
2) If ALARM appears, a dryer fault is indicated; see
Troubleshooting Guide for possible remedies. After
fault correction push Reset button to turn Fault alarm
off.
Type of FAULTS:
HIGH DISCHARGE TEMPERATURE - refrigerant
discharge temperature is above the set point.
LOW PRESSURE - the refrigeration compressor
control circuit has opened because of low suction
pressure.
HIGH PRESSURE - the refrigeration compressor
control circuit has opened because of high head
pressure. The high pressure switch must be reset
manually once the fault is corrected. Red reset button
is located on pressure switch inside unit.
HIGH EVAPORATOR TEMPERATURE - compressed
air temperature is above the set point.
COMPRESSOR - normally open (NO) auxiliary
contact on the compressor contactor is open when
the dryer is on.
HEATER - normally closed (NC) auxiliary contact on
the compressor contactor is open when the dryer is
off.
TEMP SENSOR - occurs if the temperature sensor
circuit is open or shorted. If open, none of the LED’s
in the temperature display will be illuminated. If
shorted, all the LEDs in the temperature display will
be illuminated.
DRAIN - electric drain contains a high water level
alarm that activates if drain fails to discharge.
f. Check drain operation - push Drain (push-to-test) button
to energize electric drain. A flow of condensate and/or
air should be present at the drain outlet.
2.3 Using the RS-485 Port Connector (J8)
This connector provides RS-485 compatible signals from the
internal master microprocessor. Using jumpers on the headers
supplied near the connector (J12), 120 ohm termination resistors
can be connected and the system can be connected for either
two-wire or four-wire operation (half or full duplex). To connect
the termination resistors, install jumpers on J12 in the direction
shown by the white bars printed above the connector.
If the jumpers are removed no termination of the RS-485 bus is
in effect. Usually, these jumpers must be in position for proper
operation of the bus.
J10 contains the two-wire/four-wire jumper. If the jumper is set
in W2 place, the circuit is set up for two-wire operation. If the
jumper is set in W4 place, the circuit is set up for four-wire op-
eration. Selection of jumper settings must be determined by the
customer’s system. The jumpers are supplied as standard and
are installed as shown at the factory. Be sure to set the jumpers
properly for your system.
RS-485 Pinout
Following is the pinout for J8, the RS-485 communications con-
nector.
1 A
2 B
3 Z
4 Y
When connected in two-wire mode, the bus wires may be
connected to pins 1 & 2. Also note that when in two-wire mode,
one termination resistor jumper should be removed to prevent the
termination from being too low in value. It may be stored on the top
set of pins on J12. Those pins are not connected. Please make
sure that your connections are properly made. This connector is
a 4-pin terminal block. Mating connectors are not supplied. The
electrical signals supplied by this connector are TIA/EIA-485A
compliant. A good cable should be used to transmit signals such
as Belden 3109A or equivalent.
Communication Parameters:
RS-485 Parameters
Baud Rate
19200
Data Bits
8
Parity
None
Stop Bits
1
Flow Control
None
Modbus Drop I/O
Factory Default = 1
(user adjustable 1 - 247 )
2.4 Using the USB Host Feature (J7)
The dryer controller is equipped with a USB Host port located at
J7 on the control board which allows for the connection of a USB
flash drive. The USB flash drive can be used for data logging,
event history, and installing software updates.
1. USB Data Logging
When a USB flash drive is installed in the controller it will begin to
automatically record key dryer operating parameters: timestamp,
dryer status, service timer, total compressor run timer, discharge
temperature, evaporator inlet temperature, evaporator outlet
temperature, and dryer % load.
