Omega Products D5121 User Manual
C-75
From
$
250
Basic Unit
Four Channel Analog Input
Complete Sensor to
RS-485 or RS-232C Interface
ASCII Format Command/
Response Protocol
500 V RMS Analog
Input Isolation
15-Bit Measurement
Resolution
Continuous Self-Calibration;
No Adjustments of any Kind
Programmable Digital Filter
Requires 10 V to 30 Vdc
Unregulated Supply
Transient Suppression on
RS-485 Communications Lines
Screw Terminal Plug
Connectors Supplied
The D5000 Four Channel Sensor to
Computer Modules are a family of
complete solutions designed for
data acquisition systems based
on personal computers and other
processor-based equipment with
standard serial I/O ports. The
modules convert four analog input
signals to engineering units and
transmit in ASCII format to any host
with standard RS-485 or RS-232C
ports. These modules can measure
temperature, voltage and current.
The modules provide direct
connection to a wide variety of
sensors and perform all signal
conditioning, scaling, linearization
and conversion to engineering units.
The modules contain no pots or
switches to be set. Features
such as address, baud rate, parity,
echo, etc. are selectable using
simple commands over the
communications port–without
requiring access to the module.
The selections are stored in
nonvolatile EEPROM which
maintains data even after power
is removed.
The key to the D5000 series is
that the modules are easy to use.
You do not need engineering
experience in complicated data
acquisition hardware. With the
D5000 series modules, anyone
familiar with a personal computer
can construct a data acquisition
system.
OMEGABUS
®
D5000 Series
Four Channel Sensor to Computer Interface Modules
KQSS-14U-12, $30 each, Type K
Quick Disconnect Thermocouple
D5321, $275, shown
smaller than actual size
KQSS-14U-12, $30 each, Type K Quick
Disconnect Thermocouple. Search
omega.com for more information.
$
250
Basic Unit
C-76
DIGITAL FILTER
The D5000 options include a
unique programmable single
pole digital filter. The filter is used
to smooth analog data in noisy
environments. Separate time
constants may be specified for
small and large signal changes.
Typically, a large time constant is
specified for small signal changes
to filter out noise and provide stable
output readings. A smaller time
constant may be chosen for large
signal changes to provide fast
response to such changes.
COMMUNICATIONS
The D5000 are designed to be easy
to interface to all popular computers
and terminals. All communications
to and from the module are
performed with printable ASCII
characters.
This modular approach to data
acquisition is very flexible, easy
to use and cost effective. The
modules can be mixed and
matched to fit your application.
They can be placed remote from
the host and from each other.
You can string up to 30 modules
on one set of wires by using
RS-485 with repeaters.
The D5000 Series is completely
hardware and software compatible
with the D1000, D2000, D3000 and
D4000 series and may be mixed in
any combination.
All modules are supplied with
screw-terminal plug connectors
and captive mounting hardware.
The connectors allow system
expansion, reconfiguration or
repair without disturbing field wiring.
THEORY OF OPERATION
D5000 modules are complete
four-channel data acquisition
systems. Each unit contains
analog signal conditioning circuits
optimized for a specific input type.
The amplified sensor signals are
converted to digital data with a
microprocessor-controlled
integrating A/D converter. Offset
and gain errors in the analog
circuitry are continuously monitored
and corrected using microprocessor
techniques. The D5000 converts
the digital signal data into
engineering units using look-up
tables. The resultant data is stored
in ASCII format in a memory buffer.
The modules continuously convert
data at the rate of 8 conversions
per second and store the latest
result in the buffer.
The host computer may request
data by sending simple ASCII
commands to the module.
The D5000 will instantly respond
by communicating the ASCII
buffer data back to the host.
USER OPTIONS
The D5000 offers a variety of userselectable options including choice
of address, baud rate, parity, echo,
etc. All options are selectable
using simple commands over the
communications port. All options
are stored in a nonvolatile
EEPROM which maintains
data even after power is removed.
This allows the information to
be processed with string functions
common to most high-level
anguages such as BASIC. For
computers that support standard
ports such as RS-232C, no special
machine language software drivers
are necessary for operation.
RS-232C is not designed to be
used as a multiparty system;
however, the module can be
daisy-chained to allow many
modules to be connected to a
single communications port.
In this network, any characters
transmitted by the host are received
by each module in the chain and
passed on to the next module until
the information is echoed back to
the host. If a module is correctly
addressed and receives a valid
command, it transmits a response
on the daisy chain network. The
response will be rippled through
any other modules in the chain
until it reaches the host.
RS-485 was developed for
multidropped systems that can
communicate at high data rates
over long distances. For systems
requiring many modules, high
speed or long distances,
RS-485 is recommended.
C
D1321, $325, shown smaller
than actual size
A1000, $250, RS-232 to RS-485
converter/repeater
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