Comet T3411, T3311 Instruction Manual
TRANSMITTER T3311, T3411
Programmable relative humidity and temperature transmitter
with serial output RS232 and RS485
With computing of dew point temperature, absolute humidity, specific humidity,
mixing ratio and specific enthalpy
Instruction Manual
2 IE-SNC-T33(4)11-04
Transmitter setting from the manufacturer................................................................................................. 3
Transmitter installation .............................................................................................................................. 3
Dimensions............................................................................................................................................. 4
Typical application wiring, connection of terminals.............................................................................. 5
Info mode ............................................................................................................................................... 6
Setting of transmitter, selection of communication protocol .....................................................................6
Description of communication protocols ................................................................................................... 8
Modbus RTU.......................................................................................................................................... 8
Supported functions ........................................................................................................................... 8
Jumper and button.............................................................................................................................. 8
Description of supported function ..................................................................................................... 9
03 (0x03): Reading of 16-bit registers (Read Holding Registers)........................................................ 9
04 (0x04): Reading 16-bit input gates (Read Input Registers)............................................................. 9
16 (0x10): Setting of several 16-bit registers (Write Multiple Registers) ............................................ 9
Exception Responses.......................................................................................................................... 12
Exception codes.................................................................................................................................. 12
Modbus CRC ................................................................................................................................... 12
Procedure during calculation of Modbus CRC................................................................................... 13
Modbus registers of the transmitter ................................................................................................. 13
Example of communication ............................................................................................................. 13
Reading of temperature, address 0x0031 ........................................................................................... 13
Reading of relative humidity, address 0x0032 ................................................................................... 14
Reading of computed value, address 0x0033 ..................................................................................... 14
Reading of all values at once, address block 0x0031 to 0x0033........................................................ 14
Protocol compatible with Advantech-ADAM standard....................................................................... 15
Jumper.............................................................................................................................................. 15
General syntax of commands........................................................................................................... 15
Description of supported functions.................................................................................................. 16
Configuration of transmitter............................................................................................................... 16
Response of the transmitter ................................................................................................................ 16
Check sum (CRC) .............................................................................................................................. 16
Reading of the temperature ................................................................................................................ 16
Reading of humidity........................................................................................................................... 16
Reading of computed value................................................................................................................ 17
Query to adjusted configuration ......................................................................................................... 17
Reading of device name ..................................................................................................................... 17
Reading of firmware version.............................................................................................................. 17
Format of data.................................................................................................................................. 18
Error states.......................................................................................................................................... 18
Communication protocol ARION - AMiT company........................................................................... 18
Supported frames ............................................................................................................................. 18
Supported function description ........................................................................................................ 19
Error States of the transmitter .................................................................................................................. 19
Error 0 .................................................................................................................................................. 19
Error 1 .................................................................................................................................................. 19
Error 2 .................................................................................................................................................. 20
Error 3 .................................................................................................................................................. 20
Readings on LCD display ........................................................................................................................ 20
Technical parameters of the instrument: .................................................................................................. 21
Measuring parameters:......................................................................................................................... 21
End of operation....................................................................................................................................... 22
Technical support and service .................................................................................................................. 22
Appendix A .............................................................................................................................................. 23
Connection of ELO E06D converter (RS232/RS485) ......................................................................... 23
IE-SNC-T33(4)11-04 3
Instruction Manual for use of temperature and relative humidity transmitter:
T3311 (RS232)
T3411 (RS485)
Transmitter is designed for measurement of ambient temperature and relative humidity of air
without aggressive ingredients with computing one of the following values: dew point temperature,
absolute humidity, specific humidity, mixing ratio and specific enthalpy. Please read instruction
manual before the first transmitter connection. Transmitter T3311 communicates via link RS232,
transmitter T3411 via link RS485. Supported communication protocols are Modbus RTU, protocol
compatible with standard Advantech-ADAM and ARION. Temperature and relative humidity
sensors are non-removable instrument parts. Measured and computed values are displayed on dual
line LCD display. The first line displays temperature. Value displayed on the second line is
selectable among relative humidity and computed value. It is also possible to display both readings
with cyclic overwriting in 4 seconds interval. Display can be also switched OFF totally. Output link
RS485 of transmitter T3411 is galvanic isolated. Output link RS232 of transmitter T3311 is NOT
galvanic isolated. Setting of all transmitter parameters is enabled in accordance with procedure
described in chapter „Setting of transmitter, selection of communication protocol“ or by means of
commands of selected communication protocol. For detailed description of features of protocols see
chapter „Description of communication protocols“.
Transmitter setting from the manufacturer
If special setting was not required in the order transmitter is set from the manufacturer to the
following parameters:
communication protocol: Modbus RTU
transmitter address: 01H
communication speed: 9600Bd, without parity, 2 stop bits
display: switched ON
value displayed at lower line: relative humidity only
preset computed value: dew point temperature
Transmitter installation
Transmitter is designed for wall mounting. There are two mounting holes at the sides of the
case. It is NOT recommended to use the device for long time under condensation conditions. It
could be the cause of water steam condensation inside the sensor’s cover into water phase. This
liquid phase stays inside sensor’s cover and can’t escape from the cover easily. It can dramatically
increase response time to relative humidity change. If water condensation occurs for longer time it
can cause sensor damage. Similar effect can occur under water aerosol conditions. Don’t connect
transmitter while power supply voltage is on. Interconnection terminals are accessible after
unscrewing four screws and removing the lid. Lace the cable through a gland at the case wall.
Connect the cable to terminals with respecting the signal polarity (see figure). Terminals are selfclamping and can be opened by a suitable screwdriver. For the opening, insert the screwdriver to
smaller terminal hole and lever by him. Do not forget to tighten glands and case lid with inserted
packing after cables connecting. It is necessary for warranting of protection IP65. Working position
is with the bronze filter downwards – see figure.
Transmitter T3311 is supplied with connection cable equipped with connector for connection to
RS232 interface. For T3411 transmitter (RS485) it is recommended to use shielded twisted copper
cable (e.g. SYKFY). Outside diameter of the cable must be from 3 to 6.5 mm, maximal length
1200m. The cable must be located at indoor rooms.
4 IE-SNC-T33(4)11-04
Nominal cable impedance should be 100 Ω, loop resistance max. 240 Ω, cable capacity max.
65 pF/m. Suitable cable is e.g. SYKFY 2x2x0,5 mm2, where one wire pair serves for transmitter
powering and the other pair for communication link.
The cable should be led in one line, i.e. NOT to „tree“ or „star“. Termination resistor should
be located at the end. For short distance other topology is allowed. Terminate the network by a
termination resistor. The value of the resistor is recommended about 120 Ω. For short distance
termination resistor can be left out.
The cable should not be led in parallel along power cabling. Safety distance is up to 0.5 m,
otherwise undesirable induction of interference signals can appear.
Dimensions
T3311 – RS232
T3411 – RS485
IE-SNC-T33(4)11-04 5
Typical application wiring, connection of terminals
T3311 – power from communication port T3311 – power from external voltage source
T3411 – RS485
6 IE-SNC-T33(4)11-04
Info mode
If in doubt of setting of installed transmitter, verification of its address is enabled even
without using computer. Power should be connected.
Unscrew transmitter cover and shortly press button next to connection terminals (jumper
should be opened). Actual adjusted address of transmitter is displayed on LCD display at decimal
base. Next press of button exits info mode and actual measured values are displayed.
Note: No measurement and communication is possible during info mode. If transmitter stays in info
mode for longer than 15 s, transmitter automatically returns to measuring cycle.
Setting of transmitter, selection of
communication protocol
Each new setting of transmitter parameters is stored in its internal memory1. If modification of
transmitter setting is needed (communication protocol, its parameters, setting of LCD display), it is
recommended to use of User’s software available at www.cometsystem.cz (providing all settings of
transmitter parameters) or proceed in following way (support basic setting):
• Connect transmitter with PC, for T3411 (RS485) use converter RS485/RS232.
• Run program „HyperTerminal“ on your computer – it is a part of Windows operating system
(Start → Program Files → Accessory → Communication → HyperTerminal) and set
transmission parameters. I.e. enter name of new connection (e.g. Transmitter), press button OK,
window „Connect“ appears. In field „Connect by means of“ select COM port, which transmitter
is connected to (e.g. COM1) and press OK. In following window „COM1 – Features“ enter to
field:
„Bits per second“ 9600
“Data bits“ 8
“Parity“ None
“Number of stop-bits“ 1
“Flow control“ None
Continue by pressing OK.
1
During writing to transmitter memory no power failure should appear! Such failure can cause
damage of other settings stored in the transmitter!
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• Select item „File“, „Features“ in menu. Select bookmark „Setup“, in the window, click on
„ASCII Setup... “ and modify all items in accordance with following figure and press OK
• Unscrew 4 screws of transmitter cover and remove it. Plug in jumper.
• Keep the button inside the transmitter pressed, only now you can connect power voltage and
then release the button. If transmitter is powered directly from PC communication port (for
interface RS232), it is necessary first to disconnect communication cable, then to keep the
button pressed, to connect communication cable (and also power) and only now release the
button.
• LCD display of the transmitter displays „PC“.
• Running HyperTerminal displays main menu.
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