2
type (temperature, pressure or 0-10 VDC), 3) the selection of
the used fixed stage's individual (primary or secondary) set point
values, 4) the selection of the fixed stage's activation modes [LIFO,
FIFO or Binary Encode] and 5) the three scaling percentages, used
to match the sequencer's PWM and VDC output signal's param-
eters, to the variable stage EC motors' input signal's specifications.
The 890-DSQ Sequencer is available a 6 fixed stage model, with
an additional "variable stage output". The "variable stage output"
consists of the "PWM" and "VDC" outputs and their associated
"GND" terminals. There are three sets of "VDC" outputs and
associated "GND" terminals and three sets of "PWM" (17.5 volt,
80 Hz) outputs and their associated "GND" terminals (12 termi-
nals total).
A total of 3 continuously variable, VDC and/or PWM con-
trolled, EC motors may be wired (in any combination) to the
VDC and/or PWM output terminals. For heating applications, a
maximum of 30 mA is available to operate the SCRs.
The 890-Series sequencer can be used for local, remote or a
combination of both local and remote operation. Remote opera-
tion can be implemented, at any time, by using a Modbus RTU
master computer to send the appropriate register data, listed
in Tables 2A & 2B, on pages 16 & 17, to the 890-DSQ Series
sequencer's internal data registers. The sequencer communicates
via a 3 wire Modbus RTU connection to the Modbus RTU master
computer. All of the 890-DSQ Sequencer's options, parameters
and numerical values can be read and set remotely using the
Modbus RTU connection. During remote operation, the Modbus
master reads and writes to the 890-DSQ Sequencer's 76 internal
data registers, using Modbus RTU commands 3, 6 and 16 (hexa-
decimal 10).
BUTTON LOCKOUT FEATURE: The 890-DSQ
Sequencer is equipped with a push button lockout feature. This
feature is Off (disabled) by default, but can be turned On or Off
using the menu system or remotely using the Modbus connection.
If the lockout feature is enabled and the buttons are locked, the
installer will not be able to operate the sequencer manually using
the push buttons. The LCD screen will display "Locked - Enter
Code" whenever a push button is pressed.
The buttons can be unlocked by simultaneously pressing and
holding down these four push buttons: "MODE, UP, EXIT and
ENTER" until after the word "SUCCESS" appears on the LCD
screen (approximately 2 seconds). The buttons will now operate.
Unlocked buttons can be locked by simultaneously pressing
and holding down the same four push buttons: "MODE, UP,
EXIT and ENTER" only until the words "Locked - Enter Code"
appears on the LCD screen. If the four buttons above are not
released immediately when "Locked - Enter Code" appears, the
word "SUCCESS" will appear on the LCD screen causing the
buttons to remain unlocked.
Pre-Installation Information/
Instruction
When the lockout feature is enabled, unlocked buttons will self-
lock after five (5) minutes of no button activity.
LCD BACKLIGHT FEATURE: The LCD's backlight will
remain on while checking or updating the 890-DSQ Sequencer's
selections using the push buttons. After five (5) minutes of push
button inactivity, the backlight will turn off. Pushing any button
afterwards re-activates the backlight.
RELAY FIXED STAGE TEST FEATURE: The 890-
DSQ Sequencer has a relay fixed stage test feature which allows
the installer to sequentially turn on, then turn off, each stage to
individually verify condenser fan or SCR operation (see Operating
Modes section, MODE 1, on page 4).
INPUT SENSOR VALUE FEATURE: Each of the
sequencer's used input sensor values (temperature in °F or pres-
sure in PSI) can be displayed, on the LCD, by pressing the UP
button when the LCD's screen displays the Home Screen. The
sensor values are shown across the screen from left to right. The
first three (3) sensor values are shown on the LCD screen's top line
[input one (1) on the left side] and the last three (3) sensor values
are shown on the bottom line [input sensor four (4) on the left].
Unused input values are not displayed.
The 890-DSQ Sequencers come with a pre-programmed series
of fixed relay stage set point values (turn on & off). Each one
of the relay's turn on and turn off values may be individually
adjusted, either locally or remotely to suit a particular installation.
When a unique application requires the selection of different set
points, other than the pre-programmed set points, a new set of
set point values can be automatically calculated by the sequencer's
micro controller, using equal spacing between stages. Any or all of
the programmed set point values can be updated, manually.
The selection of EC motors depends upon the end use of the
EC motor. When the EC motors will be used as variable stage
modulating motors, they must be continuously variable EC motors
that accept a 1) 0 - 10 VDC, or 2) 10 - 0 VDC or 3) 17.5 volt,
80 Hz PWM control signal. These continuously variable EC
motors do not need to have the same horsepower and maximum
rpm as the fixed rpm, staged PSC and EC motors. The ratio of
max performance can be set in the controller. However, installing
continuously variable EC motors that have the same size, line
voltage, horsepower and maximum rpm as the fixed rpm, staged
PSC motors, they are replacing, makes the installation simpler.
When the EC motors will be used as staging motors, they
should provide the same performance (size, line voltage, horse-
power, maximum rpm and airflow) as the other staged motors.
When updating a bank of 4 or 6 PSC condenser fan motors to
obtain continuous airflow across the condenser, two of the PSC
motors should be replaced with two continuously variable EC
motors, to supply enough modulating airflow, to achieve continu-
ously smooth air-flow thru the condenser coils over the sequencer's
full operating range.
When installing the 890-DSQ Sequencer in a heating system,
and the continuous vernier capability will be implemented, size the
VS (variable stage's) SCR with twice the KW capacity as a single
fixed staged heater SCR to ensure continuously smooth heating
functionality.
Description Con't
