NOVUS RHT-WM-485-LCD Temperature and Humidity Transmitter Instruction Manual
- June 3, 2024
- Novus
Table of Contents
NOVUS RHT-WM-485-LCD Temperature and Humidity Transmitter
INTRODUCTION
RHT-WM-485-LCD, RHT-DM-485-LCD and RHT-P10-485-LCD transmitters include high
accuracy and stability sensors for measuring temperature and relative
humidity. They are microprocessed devices and, therefore, allow being entirely
configured through a RS485 interface, using the Modbus RTU commands.
DigiConfig allows the configuration of all transmitters features as well as
its diagnostic procedure.
The transmitter can be configured or displaying the values of measured
temperature and Relative Humidity or the values of measured temperature and
Dew Point.
IDENTIFICATION
The identification label is fixed on the transmitter body. Check if the
features described on this label are in accordance with your order.
The RHT-WM-485-LCD and RHT-P10-485-LCD models intended for wall mounting,
while the RHT-DM-485-LCD model comes with a probe tip rod for installation in
ducts or through walls.
The following elements are located at the front side of the transmitter:
Communication Indicator
(COM): Indicates when the device is receiving data from the Modbus network.
Button (Programming): Button used for configuration of the communication
parameters and for screen changing. Temperature: Value of measured
temperature. Relative
Humidity: Value of measured relative humidity.
Communication Address:
Value programmed for identifying the transmitter of the Modbus network.
Programmable between 1 and 247.
SPECIFICATIONS
Operating temperature of the transmitter| From -40 °C to
70 °C
Sensor and Rod ( RHT-DM ): See Figure 3.
---|---
Electromagnetic compatibility| EM 61326:2000
Sensor measuring range
| Temperature: -40.0 °C to 100.0 °C.
Relative Humidity (RH): 0.0 to 100.0 % RH (No Condensing).
Dew Point: -40.0 °C and 100.0 °C.
Measurement accuracy| See Figure 3.
Note : a small measurement error can be eliminated adjusting the
OFFSET parameter of the software.
Measuring resolution| Temperature: 0.1 °C.
14 bits (16383 levels)
Relative Humidity (RH): 0.1 %. 12 bits (4095 levels)
Response time| Temperature: up to 30 s in slow air movement.
Humidity: up to 8 s in smooth air movement (20 to 80 % RH).
Sampling interval| 3 seconds
Power supply| 12 Vdc to 30 Vdc, consumption < 16 mA
Housing| Polycarbonate
Protection class| Product appropriate for applications which require
protection class up to IP65.
Electronic module case: IP65. Sensor capsule: IP40.
Dimensions| 60 x 70 x 35 mm
DigiConfig software operation environment| Configuration software for
Windows 98, NT, 2000, XP and Vista. Menus in Portuguese, English or Spanish.
Configures, reads, and exhibits data on the screen.
Accessories
| 1.5 m long communication cable is part of the product or can be purchased separately (PN: 8813099999).
MEASUREMENT ACCURACY AND OPERATIONAL LIMITS OF THE SENSORS
MECHANICAL INSTALLATION
The RHT-DM-485-LCD (Duct Mount) model transmitter must be installed with a flange. This flange is first screwed onto the duct wall, and the transmitter probe is then inserted into the flange central hole and locked. Fig. 4 below shows flange dimensions and holes. Available in stainless steel or polyamide 6.6.
The probe is made in stainless steel, with standard lengths of 150 mm or 250 mm.
The RHT-WM-485-LCD (Wall Mount) model is designed for wall mounting. Removing
the transmitter cover gives the user access to two bores for fixing the base,
as shown in the figure below.
The transmitter must be fixed with the sensor capsule directed downwards to
assure the specific accuracy and protection level
Figure 7 – Dimensions of the RHT-WM-485-LCD model
The RHT-P10-485-LCD electronic housing is designed for wall mounting, while
its remote sensor probe is intended for inserting and screwing in a flange.
Figure 9 – Mounting flange
Note: The flange is not bundled with the transmitter. It must be ordered
separately.
ELECTRICAL INSTALLATION
ELECTRICAL CONNECTIONS
The Fig.10 below shows the necessary electrical connection. The terminals 1,
2, 3 and 4 are intended for connection.
| 1 | – VCC | Power supply | Black wire |
|---|---|---|---|
| 2 | + VCC | Power supply | White wire |
| 3 | D1 | D | D+ |
| 4 | D0 | D- |
Be careful when connecting the power supply wires to the RHT-WM-485-LCD, RHT-
DM-485-LCD and RHT-P10-485-LCD Transmitter.
If the positive wire from the power source is connected, even momentarily, to
one of the communication connection terminals, the transmitter may be damaged.
INSTALLATION RECOMMENDATIONS
- Small electric signal conductors must pass through the system plant separated from the actuating conductors or from high current or voltage lines. If possible, inside grounded conduits.
- The power supply of the instruments must be provided from a proper network for instrumentation.
- In control and monitoring applications it is essential to consider what can happen if any part of the system should fail.
- We recommend the use of RC FILTERS (47Ω and 100nF, series) in parallel with contactor and solenoid coils etc.
CONFIGURATION / OPERATION
The user will receive the transmitter perfectly calibrated, without the need
for any adjustments. The configuration performed at the factory has the
following characteristics:
Addr (Communication Address) = 247
baVd (Communication speed) = 115200
par (Parity) = Par
DigiConfig for Windows is a software used for configuration of the RHT-
WM-485-LCD, RHT-DM-485-LCD and RHT-P10-485-LCD transmitters. For its
installation, run the “DigiConfigSetup.exe” and follow the instructions as
shown.
DigiConfig comes with an unabridged help tutorial, containing all the
necessary information for you to use it. If you want to use help tutorial,
start the application, and select the Help menu or press F1.
Access the site www.novusautomation.com to obtain the installer for DigiConfig
and the additional manuals.
SCREENS OF THE TRANSMITTER
Indication screen for the measured values in the transmitter:
1ª Screen: Main
For configuring the communication parameters, press the button (± 5 seconds)
until the screen starts blinking, then release the button and press it again
to increment. When the desired value appears, release the button, and wait
until the screen stops blinking (± 10 seconds). To access the next screens,
press the button.
Configuration screen for the Modbus Address: Defines the address of the module
within the Modbus network. Values between 1 and 247.
2ª Screen: Modbus Address
Configuration screen for the Baud Rate: Defines the Modbus communication
speed. Valid values: 1,200, 2,400, 4,800, 9,600, 19,200, 38,400, 57,600 and
115,200.
3ª Screen: Baud Rate
Configuration screen for the Parity: Defines the parity code used for Modbus
communication. Value 0 (none), 1 (odd) and 2 (even).
4ª Screen: Parity
Read-only screens of the values measured by the transmitter:
7ª Screen: Dew Point
SERIAL COMMUNICATION
The transmitter is provided with RS485 serial communication, operating as a
slave within the Modbus RTU network. The configuration of the transmitter is
performed through the serial (RS485) interface. For configuring the
communication parameters, you can use the programming button.
In this section you will find the instructions necessary to perform the data
reading without using the DigiConfig software. To assure correct configuration
of the transmitter, always use the DigiConfig software. After being
configured, the input data may be accessed by any other software capable for
Modbus RTU communication.
MODBUS COMMANDS
The Modbus RTU commands (functions) listed in the table below are implemented.
For further information with respect to each of these commands and the Modbus
protocol in general, please access the site www.modbus.org.
READ HOLDING REGISTERS – 0x03
This command can be used for reading the value of one or several holding
registers, according to the Holding Registers Table.
WRITE HOLDING REGISTERS – 0x06
This command can be used for writing in a holding register, according to the
Holding Registers Table.
HOLDING REGISTERS TABLE
The specified addresses correspond to the low-level physical addresses, where
zero (0) corresponds to the PLC 40001 address. The Minimum and Maximum columns
show the range of values valid for each parameter. The R/W column indicates if
the parameter is for reading and writing (R/W) or for reading only (R).
DESCRIPTION OF SOME REGISTERS
REGISTER 2 – BAUD RATE
Defines the Modbus communication speed. The transmitter comes factory-
configured with a Baud-Rate of 115200.
| CODE | BAUD RATE |
|---|---|
| 0 | 1.200 |
| 1 | 2.400 |
| 2 | 4.800 |
| 3 | 9.600 |
| 4 | 19.200 |
| 5 | 38.400 |
| 6 | 57.600 |
| 7 | 115.200 |
REGISTER 3 – MODBUS ADDRESS
Defines the address of the transmitter within the Modbus network. Values
between 1 and 247. The transmitter comes factory-configured with address 247.
REGISTER 4 – PARITY
Defines the parity code used for Modbus communication. The transmitter comes
factory-configured with parity even.
| CODE | PARITY |
|---|---|
| 0 | None |
| 1 | Odd |
| 2 | Even |
| ADDRESS | DESCRIPTION |
| --- | --- |
| 0 | Serial number (word high) |
| 1 | Serial number (word low) |
| 2 | Baud-Rate |
| 3 | Modbus Address |
| 4 | Parity |
| 5 | Firmware release |
| 6 | Indication mode |
| 7 | Temperature value (°C or °F)* |
| 8 | Relative humidity value (%)* |
| 9 | Dew point value (°C or °F)* |
| 10 | Configuration of measurement unit |
| 11 | Disables configuration via button |
| 12 | User offset for temperature* |
| 13 | Reserved |
| 14 | User offset for humidity* |
| 15 | Reserved |
| 16 | Error value |
| 17 | Title |
| 18 | Title |
| 19 | Title |
| 20 | Title |
| 21 | Title |
| 62 | Model |
REGISTER 6 – INDICATION MODE
Defines the indication mode on the display of the sensor values readout. The
transmitter comes factory-configured with indication of temperature and
relative humidity.
| CODE | DESCRIPTION |
|---|---|
| 0 | Indicates temperature and relative humidity. |
| 1 | Indicates temperature and dew point. |
| 2 | Indicates relative humidity and dew point. |
| 3 | Indicates temperature only. |
- REGISTER 7 – TEMPERATURE VALUE (°C or °F)
- REGISTER 8 – RELATIVE HUMIDITY VALUE (%)
- REGISTER 9 – DEW POINT VALUE (°C or °F)
Shows the measured value in engineering units. The decimal point is fixed at one place, the value is exhibited without the decimal point and must be considered by the reading software.
REGISTER 10 – CONFIGURATION OF MEASUREMENT UNIT
Defines the measurement unit for the temperature and the dew point. The
transmitter comes factory-configured for degrees Celsius (°C).
| CODE | UNIT |
|---|---|
| 0 | °C |
| 1 | °F |
REGISTER 11 – DISABLES CONFIGURATION VIA BUTTON
Defines the changes of configuration via button.
| CODE | DESCRIPTION |
|---|---|
| 0 | Factory-configured default value. |
| 1 | Disables the configuration change of communication parameters via button. |
REGISTER 12 – USER OFFSET FOR TEMPERATURE
Defines the user Offset value in engineering units for the temperature. The
transmitter comes factory-configured with the Offset value equal to 0 (zero).
REGISTER 14 – USER OFFSET FOR HUMIDITY
Defines the user Offset value in engineering units for the relative humidity.
The transmitter comes factory-configured with the Offset value equal to 0
(zero).
REGISTER 16 – ERROR VALUE
Shows the error value which is transmitted when the sensor has a problem. The
transmitter comes factory-configured with the value -9999.
SPECIAL CARE
The transmitter is an electronic module and, therefore, will need some special care when handling it:
CARE WITH SENSORS
The calibration of the humidity sensor may be changed if it is exposed to contaminant vapors or extreme humidity and temperature conditions for long time periods. For accelerating the calibration recovery follow the procedure as described below:
- Remove the sensor from the capsule.
- if there are solid particles on the sensor, wash it with water.
- Place the sensor within 80 °C (+/- 10 °C) oven for 24 hours.
- Keep the sensor in a place at a temperature between 20 and 30 °C and humidity over 75 % RH for 48 hours.