ETC2 D5142M Modbus rtu or dgh ascii communications protocol Datasheet

D5000M SERIES FOUR CHANNEL
SENSOR TO COMPUTER INTERFACE MODULES
D5000M FEATURES
• Four analog input channels.
• Complete sensor to RS-485 or RS-232 interface.
• Modbus RTU or DGH ASCII communications protocol.
• 500V rms analog input isolation.
• 15 bit measurement resolution.
• Continuous self-calibration; no adjustments of any kind.
• Programmable digital filter.
• Requires +10V to +30Vdc unregulated supply.
• Transient suppression on RS-485 communications lines.
• Screw terminal plug connectors supplied.
• CE marked.
APPLICATIONS
• Process monitoring and control
• Remote data logging to any host computer
• Product testing
• Direct connection to modems
• Direct connection to PLC.
GENERAL DESCRIPTION
The D5000M series are similar to the D5000 series but
use the Modbus RTU protocol for communication. The
modules convert four analog input signals to engineering
units and transmit in ASCII format to any host with standard RS-485 or RS-232 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, and
scaling 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.
D5000M SPECIFICATIONS (typical at +25°C and nominal power supply unless otherwise noted)
Analog
• Four channel analog input.
• Maximum CMV, input to output at 60Hz: 500V rms.
• Leakage I, input to output at 115Vrms, 60Hz: <2µA rms.
• 15 bit measurement resolution.
• 8 conversions per second.
• Common mode rejection: 100dB at 50/60Hz.
• Autozero & autocalibration—no adjustment pots.
Digital
• 8-bit CMOS microcomputer.
• Digital scaling, linearization and calibration.
• Nonvolatile memory eliminates pots and switches.
• Small and large signal digital filtering with user selectable
time constants.
Communications
• Communications in ASCII via RS-232C, RS-485 ports.
• Selectable baud rates: 300, 600, 1200, 2400, 4800,
9600, 19200, 38400, 57600, 115200.
• NRZ asynchronous data format; 1 start bit, 7 data bits,
1 parity bit and 1 stop bit.
• Parity: odd, even, none.
• User selectable channel address.
• Modbus RTU or DGH ASCII communications protocol.
• Up to 247 multidrop modules per host serial port.
• Communications distance up to 4,000 feet (RS-485).
• Transient suppression on RS-485 communications lines.
• Communications error checking via checksum.
• All communications setups stored in EEPROM.
Power
Requirements: Unregulated +10V to +30Vdc, 0.75W max
Protected against power supply reversals.
Environmental
Temperature Range: Operating -25°C to +70°C.
Storage -25°C to +85°C.
Relative Humidity: 0 to 95% noncondensing.
Warranty
12 months on workmanship and material.
D5100M Voltage Inputs
• Voltages: ±100mV, ±1V, ±5V, ±10V, ±100Vdc.
• Resolution: 0.01% of FS (4 digits).
• Accuracy: ±0.02% of FS max.
• Zero drift: ±1 count max (autozero).
• Span tempco: ±50ppm/°C max.
• Input burnout protection to 250Vac .
• Input impedance: ≤ ±1V input =100MΩ min.
≥ ±5V input =1MΩ min.
D5200M Current Input
• Current: 4-20mAdc.
• Resolution: 0.04% of FS.
• Accuracy: 0.04% of FS.
• Zero drift: ±1 count max (autozero).
• Span tempco: ±50ppm/°C max.
• Voltage drop: 1.0V max.
D5300M Thermocouple Inputs
• Thermocouple types: J, K, T, E (factory set).
• Ranges: J = -200°C to +760°C
T = -200°C to +400°C
K = -150°C to +1250°C E = -100°C to +1000°C
• Resolution: ±1°.
• Overall Accuracy (error from all sources) from 0 to +40°C
ambient: ±1.0 °C .
• Input impedance: 100MΩ min.
• Lead resistance effect: <20µV per 350Ω.
• Open thermocouple and overrange indication.
• Input burnout protection to 250Vac.
• Automatic cold junction compensation and linearization.
D5450M Thermistor Inputs
• Thermistor types: 2252Ω at 25°C.
• Range: -0°C to +100°C.
• Resolution: 0.01°C or F.
• Accuracy: ±0.1°C.
• Input protection to 30Vdc .
D5000M Mechanicals and Dimensions
Case: ABS with captive hardware.
Connectors: Screw terminal barrier plug (supplied).
Replace with Phoenix MSTB 1.5/10 ST 5.08 or equivalent.
Specifications are subject to change without notice.
NOTE: Spacing for mounting screws = 2.700" (6.858 cm).
Screw threads are 6 X 32.
General Description (Continued)
The key to the DGH product concept is that the modules
are easy to use. You do not need engineering experience
in complicated data acquisition hardware. With the DGH
modules, anyone familiar with a personal computer can
construct a data acquisition system. 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.
The D5000M series is completely hardware and softwarecompatible with the DGH D1000, D2000, D3000 and
D4000 series and may be mixed in any combination.
All modules are supplied with removeable screw-terminal
connectors and captive mounting hardware. The connectors allow system expansion, reconfiguration or repair
without disturbing field wiring.
THEORY OF OPERATION
D5000M 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 D5000M 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.
Host processors may request data by sending a query
to the module. The D5000M will instantly respond by
communicating the memory buffer data back to the
host processor. Up to 247 modules may be linked to a
single RS-485 port or one module to a RS-232C port.
Each module on a serial line is identified by a unique
user-programmable address. This addressing technique allows modules to be interrogated in any order.
with string functions common to most high-level languages
such as BASIC. For computers that support standard ports
such as RS-232, no special machine language software
drivers are necessary for operation. The modules can also
be connected to auto-answer modems for long-distance
operation without the need for a remote supervisory
computer. The ASCII format makes system debugging
easy with a dumb terminal.
Because the Modbus protocol does not support echoing
D5000M RS-232 modules may not be daisy-chained. This
limits you to one four-channel module per RS-232 port.
RS-485 was developed for multidropped systems that can
communicate at high data rates over long distances. RS485 receivers can handle common mode voltages from -7
to +12V without loss of data, making them ideal for transmission over great distances. Since an RS-485 system
cannot transmit and receive at the same time it is a halfduplex system. For systems requiring many modules,
high speed or long distances RS-485 is recommended.
COMMAND SET
The D5000M series uses the Modbus RTU or the
DGH ASCII protocol for communication.
The Modbus RTU binary protocol uses a master-slave
technique, in which only the master device can initiate
transactions. The slave devices respond by supplying
the requested data to the master or by taking the action requested in the query. The master can address
any slave device. The returned messages are considered response messages. The supported master
codes are:
Modbus RTU Functions and Descriptions
04 Read Input Register (Analog Inputs)
06 Preset Single Register (DGH/RTU Protocol)
The DGH ASCII protocol is a command and response
protocol using ASCII characters for easy troubleshooting
and interpretation of data values.
D5000M Series ASCII Command Set.
DIGITAL FILTER
The D5000M 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 D5000M 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 allows the information to be processed
Command and Definition
MBD
RD
RMA
RS
RZ
WE
Modbus Disable
Read Data
Read Module Address
Read Setup
Read Zero
Write Enable
Write Protected Commands.
CZ
Clear Zero
RR
Remote Reset
SU
Setup Module
TS
Trim Span
TZ
Trim Zero
MBR Write Slave Address
Typical
Command
Message
($ prompt)
$1MBD
$1RD
$1RMA
$1RS
$1RZ
$1WE
Typical
Response
Message
*
*+00072.00
*0102
*31070142
*+00000.00
*
$1CZ
$1RR
$1SU31070142
$1TS+00600.00
$1TZ+00000.00
$MBR01
*
*
*
*
*
*
SETUP
The D5000M series are initiated at the factory using the
DGH ASCII protocol. This allows setup and configuration,
including the Modbus device address, to be easily performed using the DGH setup software or a dumb terminal.
Each D5000M module must be properly configured before
installation into a Modbus system.
UTILITY SOFTWARE
Complimentary Utility Software is included with each purchase order. The software is compatible with Windows 95, 98,
NT 4.0+, 2000 operating systems and distributed on CDROM. The Utility Software simplifies configuration of all userselectable options such as device address, baud rate and
filtering constants. The latest version of our software is always
downloadable from our web site at www.dghcorp.com.
PROCESS CONTROL SOFTWARE
Modbus RTU protocol is supported by virtually all commercial process control software programs available today. These programs operate on IBM and compatible personal computers in the Windows 95, 98, NT and IBM OS/2
environments.
ORDERING GUIDE
MODEL INPUT/OUTPUT
Voltage Inputs
D5111M 100mV Input/RS-232 Output
D5112M 100mV Input/RS-485 Output
D5121M 1V Input/RS-232 Output
D5122M 1V Input/RS-485 Output
D5131M 5V Input/RS-232 Output
D5132M 5V Input/RS-485 Output
D5141M 10V Input/RS-232 Output
D5142M 10V Input/RS-485 Output
D5151M 100V Input/RS-232 Output
D5152M 100V Input/RS-485 Output
Current Input
D5251M 4-20mA Input/RS-232 Output
D5252M 4-20mA Input/RS-485 Output
MODEL INPUT/OUTPUT
Thermocouple Inputs
D5311M J Thermocouple Input/RS-232 Output
D5312M J Thermocouple Input/RS-485 Output
D5321M K Thermocouple Input/RS-232 Output
D5322M K Thermocouple Input/RS-485 Output
D5331M T Thermocouple Input/RS-232 Output
D5332M T Thermocouple Input/RS-485 Output
D5341M E Thermocouple Input/RS-232 Output
D5342M E Thermocouple Input/RS-485 Output
Thermistor Inputs
D5451M 2252Ω Thermistor Input/RS-232 Output
D5452M 2252Ω Thermistor Input/RS-485 Output
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