Control Modules; Red Led; Green Led; Processor Module (Psio1) - Carrier 48FP Controls Operation And Troubleshooting

Table 61 — Refrigerant Pressure
Transducer Configuration
KEYPAD
HSIO ENTRY
DISPLAY
LOG ON
LOGGED
ENTER
ON
FACT
CFG
SPB
CALB
SPB
ENTER
CALB
SPA CALB
SPA CALB
ENTER
DPB
CALB
DPB
ENTER
CALB
DPA CALB
DPA CALB
ENTER
LEGEND
DPA — Discharge Pressure, Circuit A
DPB — Discharge Pressure, Circuit B
— Suction Pressure, Circuit A
SPA
SPB — Suction Pressure, Circuit B
Table 62 — Verification of Refrigerant Pressure
Transducer Calibration
HSIO KEYPAD
ENTRY DISPLAY
PRESSURE
DPA X
SPA X
DPB X
SPB X

Control Modules

Turn controller power off before servicing controls. This
ensures safety and prevents damage to controller.
PROCESSOR MODULE (PSIO1), CONTROL OPTION
MODULE (PSIO2), AND HIGH-VOLTAGE RELAY
MODULES (DSIO1 and DSIO2) — The PSIO and DSIO
modules all perform continuous diagnostic evaluations of the
condition of the hardware. Proper operation of these modules is
indicated by LEDs (light-emitting diodes) on the front surface
of the DSIOs, and on the top horizontal surface of the PSIOs.
RED LED — If the red LED is blinking continuously at a
3- to 5-second rate, it indicates proper operation. If it is lighted
continuously, there is a problem requiring replacement of mod-
ule. If it is off continuously, power should be checked. If there
is no input power, check fuses. If fuse is bad, check for shorted
secondary of transformer or for bad module. On the PSIO1
module, if the light is blinking at a rate of twice per second, the
module should be replaced.
GREEN LED — On the PSIOs, this is the green LED closest
to COMM connectors. The other green LED on the module in-
dicates external communications, when used. Green LED
ACTION BEING
TAKEN
Enter login function
Logging in
Enter factory
configuration function
Calibrate SPB transducer
Calibrate SPA transducer
Calibrate DPB transducer
Calibrate DPA transducer
READING NAME
(EXPECTED DISPLAY)
System pressures
Discharge pressure,
circuit A (0.0 psig)
Suction pressure,
circuit A (0.0 psig)
Discharge pressure,
circuit B (0.0 psig)
Suction pressure,
circuit B (0.0 psig)
should always be blinking when power is on. It indicates
modules are communicating properly. If green LED is not
blinking, check red LED. If red LED is normal, check module
address switches. See Fig. 42. Proper addresses are:
PSIO1 (Processor Module) — 01 (may be different when
CCN connected)
DSIO1 (High-Voltage Relay Module) — 19
DSIO2 (High-Voltage Relay Module) — 49
PSIO2 (Control Options Module) — 31
If all modules indicate communication failure, check
COMM plug on PSIO1 module for proper seating. If a good
connection is assured and condition persists, replace PSIO1
module.
If only DSIO(s) or PSIO2 module indicates communication
failure, check COMM plug on that module for proper seating.
If a good connection is assured and condition persists, replace
DSIO or PSIO2 module(s).
All system operating intelligence rests in PSIO1 module,
the module that controls unit. This module monitors conditions
through input and output ports and through DSIO modules.
The machine operator communicates with microprocessor
through keypad and display module (HSIO). Communication
between PSIO1 and other modules is accomplished by a 3-wire
sensor bus. These 3 wires run in parallel from module to
module.
On sensor bus terminal strips, terminal 1 of PSIO1 module
is connected to terminal 1 of each of the other modules. Termi-
nals 2 and 3 are connected in the same manner. See Fig. 43. If a
terminal 2 wire is connected to terminal 1, system does not
work.
Internal communications between control modules in the
rooftop unit is carried out through the COMM3 communica-
tions bus. A 3-wire bus is routed between the COMM3 plugs
of each module.
The COMM1 communications bus (Fig. 44) is for external
communications to other equipment on the bus or to a comput-
er running ComfortWORKS® or Service Tool software. A
connection is usually made between the PSIO1 COMM1 plug
on the rooftop unit, the air terminals, and the other rooftop
units. A plug is provided in the control panel for connecting the
external bus to the rooftop units. The external connection plug
is factory wired to the PSIO1 COMM1 plug.
The PSIO1, DSIO1, and HSIO are all powered from a com-
mon 21-vac power source which connects to terminals 1 and 2
of power input strip on each module. A separate source of
21-vac power is used to power the DSIO2 module and PSIO2
options module through terminals 1 and 2 on power input strip.
PROCESSOR MODULE (PSIO1) (Fig. 45)
Inputs — Each input channel has 3 terminals; only 2 of the
terminals are used. Unit application determines which termi-
nals are used.
Outputs — Output is 24 vdc. There are 3 terminals, only 2 of
which are used, depending on application. Refer to unit wiring
diagram.
NOTE: Address switches (see Fig. 45) must be set at 01 (dif-
ferent when CCN connected).

HIGH-VOLTAGE RELAY MODULES (DSIO1 and 2)

(Fig. 46)
Inputs — Inputs on strip J3 are discrete inputs (ON/OFF).
When 24-vac power is applied across the 2 terminals in a chan-
nel it reads as an on signal. Zero v reads as an off signal.
Outputs — Terminal strips J4 and J5 are internal relays
whose coils are powered-up and powered-off by a signal from
microprocessor. The relays switch the circuit to which they are
connected. No power is supplied to these connections by DSIO
modules.
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