XS0-J6 - Volume flow MODBUS, RJ12 | TROX GmbH

Bus interface Modbus RTU


Volume flow controller - static transducer


X-AIRCONTROL zone module Modbus


RJ12 socket


Control component for type TVE




Compact device for use with VAV terminal units TVE

  • Controller, static differential pressure transducer and actuator in one casing
  • Use in ventilation and air conditioning systems, with clean and contaminated air
  • Simple plug connection RJ12 for supply voltage and data transmission
  • Compatible with X-AIRCONTROL zone module Modbus
  • Volume flow rates qvmin and qvmax are pre-set in the factory and saved in the controller as adjustable parameters
  • High data transparency through standardised bus communication Modbus RTU, RS485
  • Setpoint value defaults, override controls, parameter adjustment via Modbus register
  • Integral display for volume flow rates, operating modes and setting of operating parameters
  • Service access for manual adjustment devices and PC configuration software


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General information


  • All-in-one control devices for VAV terminal units
  • Static differential pressure transducer, electronic controller, and actuator are fitted together in one casing
  • Static pressure transducer for broader range of applications with clean and contaminated air, e.g. extract air that contains dust and fluff
  • Suitable for different control tasks depending on the defaulting of the setpoint value
  • Suitable for X-AIRCONTROL room control, Modbus zone module

  • Variable volume flow rate control based on temperature, humidity or air quality, for example, with the setpoint value default being transmitted via a communication interface

  • Simple connection for supply voltage and data transmission with common plug connection RJ12

  • Override controls for activating qvmin, qvmax, shut-off, OPEN position via Modbus register possible
  • Volume flow rate actual value is available as a network data point
  • Damper blade position is available as a network data point

Control strategy

  • The volume flow controller works independently of the duct pressure
  • Differential pressure fluctuations do not result in permanent volume flow rate changes
  • To prevent the control from becoming unstable, a dead band is allowed within which the damper blade does not move.
  • Flow rate range is set in the controller at the factory (qvmin: minimum volume flow rate, qvmax: maximum volume flow rate)
  • Operating parameters are specified via the order code and set in the factory

Operating modes

  • Modbus (M): setpoint value default via X-AIRCONTROL

Communication interface

  • Modbus RTU, RS485
  • List of data points, see Modbus register list

Parts and characteristics

  • Transducer for static pressure measurements
  • Overload protection
  • Connection socket RJ12 with cover
  • Display and operating elements for simple menu guidance
  • Menu guidance for adjusting operating parameters and communication interface
  • Service interface


  • TROVM-024T-05I-DS10-MB with plug connection RJ12
  • Can only be used for type TVE


  • Due to the volume flow rates set in the factory, always ensure that the control units are only installed in the specified locations
  • Commissioning steps for network integration required
  • Operating parameters can be adjusted by the customer (using the display, adjustment device or Modbus register)

Useful additions

  • Adjustment device type GUIV3-M (order code AT-VAV-G3)
  • Room control X-AIRCONTROL
    with zone module Modbus X-AIR-ZMO-MOD

Technical information

Function, Specification text, Order code

  • Function

① Differential pressure transducer
② Actuator
③ Volume flow controller
④ Setpoint value via Modbus or analogue signal
⑤ Shaft with effective pressure channel

VAV terminal units control the volume flow in a closed loop, i.e. measurement - comparison - correction. The volume flow rate is measured via the differential pressure (effective pressure). This is done using a differential pressure sensor. An integral differential pressure transducer converts the effective pressure into a voltage signal. The volume flow rate actual value is available as a data point. The factory setting is such that 100 % correspond to the nominal volume flow rate (qvnom). The volume flow rate setpoint value defaults from a higher-level controller (e.g. room temperature controller, air quality controller, central BMS). Variable volume flow control results in a value between qvmin and qvmax. It is possible to override the room temperature control, e.g. by a complete shut-off of the duct. The controller compares the volume flow rate setpoint value to the actual value and controls the integral actuator accordingly.


  • Compact controller for volume flow rate.
  • Control according to a constant or variable volume flow rate setpoint
  • Electronic controller for applying a reference value and capturing an actual value for integration into the X-AIRCONTROL
  • The actual value is based on the nominal volume flow rate such that commissioning and subsequent adjustment are simplified


  • Static transducer for clean and contaminated air in ventilation and air conditioning systems

Supply voltage

  • 24 V AC / DC


  • Integral; slow-running (running time 100 s for 90°)

Installation orientation

  • Not critical


  • Modbus RTU (RS-485)


  • Connection socket RJ12 for simple connection with X-AIRCONTROL, with rubber cap
  • Suitable for X-AIRCONTROL zone module X-AIR-ZMO-MOD

Interface information

  • Modbus: including volume flow rate setpoint value and actual value signal, damper blade position, override control

Special functions

  • Clearly visible external indicator light for indicating the functions: Set, not set, and power failure
  • Display for actual values, parameter setting and for test functions
  • Activation qvmin, qvmax, closed, open by X-AIRCONTROL

Parameter setting

  • Parameters specific to VAV terminal unit are set at the factory
  • Operating values: qvmin, qvmax factory set
  • Subsequent adjustment via display and control element directly on the device or with optional tools: adjustment device, PC software (cable connection in each case), in Modbus mode also via Modbus register access

Factory condition

  • Electronic controller factory-mounted on the terminal unit
  • Factory set parameters
  • Functional test under air; certified with sticker

TVED / 200 / D2 / XS0-J6 / M / qvminqvmaxm³/h
1 Type
TVE VAV terminal unit

2 Acoustic cladding
No entry required: No acoustic cladding
D With acoustic cladding

3 Material
No entry required: Galvanised sheet steel (standard construction)
P1 Duct powder-coated RAL 7001, silver grey
A2 Duct made of stainless steel

5 Nominal size [mm]
100, 125, 160, 200, 250, 300, 400

6 Accessories
No entry required: None
D2 Double lip seal both ends
G2 Matching flanges for both ends

7 Attachments (control components)
XS0-J6 Volume flow controller, Modbus RTU interface, display, RJ12 socket (for X-AIRCONTROL)

8 Operating mode
Modbus RTU interface, variable operation (setpoint value setting via Modbus register)

9 Operating values for factory setting
Volume flow rate [m³/h or l/s]
qvmin – qvmax

10 Volume flow rate unit
m³/h Cubic metres per hour
l/s Litres per hour

Order example: TVE–D/200/D2/XS0-J6/M/20-350 m³/h

Acoustic claddingWith acoustic cladding
MaterialGalvanised sheet steel
Nominal size [mm]200
AccessoriesDouble lip seal both ends
AttachmentVolume flow controller, Modbus RTU interface, display, RJ12 socket (for X-AIRCONTROL)
Operating modeModbus RTU interface, variable operation
Operating values for factory setting20 – 350
Volume flow rate unitm³/h



Product details, Technical data


Product details

Modbus mode (order code, operating mode M)

For smooth data exchange in the Modbus RTU network, the communication parameters and user address must be set for the Modbus interface.

The interface offers standardised Modbus register access to the available data points via the functions ReadHoldingRegister (3) and WriteSingleRegister (6).

Setpoint value default setting

  • In the operating mode M, the setpoint defaults as a percentage [%] in the Modbus register 0.
  • The transferred percentage value refers to the volume flow rate range specified by qvmin – qvmax.
  • Volume flow rate range qvmin – qvmax is set at the factory as per the order key data
  • Subsequent adjustment of qvmin or qvmax is possible in the setup menu on the display, with the adjustment device or using the Modbus interface or X-AIRCONTROL.

Actual value as feedback

  • The actual volume flow rate can be called up using the display, adjustment device or X-AIRCONTROL
  • In addition to the volume flow rate actual value, further information can be read out via X-AIRCONTROL

Override control options

For special operating situations, the volume flow controller can be put in a special operating mode (override control).

The following modes are possible: control qvmin, control qvmax, damper blade in the OPEN position or damper blade CLOSED.

  • This is set via X-AIRCONTROL.

Override control for bus timeout monitoring:

  • When there is a failure in communication, the controller executes the last saved status as a result of its factory setting. Using suitable software, the factory setting can be changed via the Modbus register 108. Each communication resets the timeout of the bus failure monitoring.

Override controls for diagnostic purposes

Activation of the diagnostic menu on the display of the controller or via X-AIRCONTROL.

Prioritisation of various default setting options

Defaults via service tools are prioritised over Modbus defaults.

  • Highest priority: defaults via the service connector (adjustment device, PC software) for test purposes
  • Lowest priority: defaults via Modbus 1 or the diagnostic menu on the controller

Compact controllers for VAV terminal units

VAV terminal unitsType of installation component

Part number





Compact controller TROVM-024T-05I-DS10-MB with connection socket RJ12

Supply voltage (AC)24 V AC ± 20%, 50/60 Hz
Supply voltage (DC)24 V DC ± 20 %
Power rating (AC)NW 100 – 200: max. 4 VA
NW 250 – 400: max. 7 VA
Power rating (DC)NW 100 – 200: max. 2.5 W
NW 250 – 400: max. 4 W
Run time for 90°100 s
Setpoint value signal input (analogue optional)0 – 10 V DC, Ra > 100 kΩ
or 2 - 10V DC Ra> 50 kΩ
Actual value signal output0 – 10 V DC or 2 – 10 V DC; 0.5 mA max.
IEC protection classIII (protective extra-low voltage)
Protection levelIP 42 (with the terminal cover attached)
EC conformityEMC to 2014/30/EU
Bus connectionModbus RTU, RS485
Number of nodes128
Adjustable communication parameters1200 – 115,200 Bd
Start bit: 1
Data bits: 8
Stop bits: 1 or 2
Parity: None, Even, Odd
Setpoint / actual value interface (Modbus)

Via X-AIRCONTROL/Modus register list

Cable terminationExternally required



Interface configuration of control component

The communication interface of the control component is pre-set to Modbus at the factory for use with the X-AIRCONTROL zone module.  Only the Modbus address must be adjusted by others for supply air or extract air.  For other applications, data transmission speed and format must be adapted according to the network environment. Using the analogue interface is not possible in combination with the connection socket RJ12 of the variant XS0-J6. For this reason, the configuration register (interface mode) must not be changed by others. To use an analogue interface, the variant XS0 is used.

Setpoint value default setting via:Actual values via:Corresponds to order key optionMenu configuration (Mode)
Analogue operationAnalogue 0 – 10 VAnalogue 0 – 10 VV or FCA0
Analogue operationAnalogue 2 – 10 VAnalogue 2 – 10 VV or FCA2
Modbus operationModbus register setpointModbus register actual value or analogue 2 - 10VMCB

Communication interface Modbus RTU (operating mode M)


MeaningAccess rightStorage
Volume flow rate setpoint value [%]
Reference: Vmin – Vmax (qvmin – qvmax)
Resolution: 0 – 10000
Volume flow rate setpoint value: 0.00 – 100.00%
1Activation of an override control; 0 = None; 1 = Open; 2 = Close; 3 = Vmin; 4 = VmaxR, WRAM
2Command triggering 0 = none; 1 = adaptation; 2 = test run; 4 = controller resetR, WRAM
4Current damper blade position [%]
Resolution: 0 – 10000
Damper blade position: 0.00 – 100.00%
5Current damper blade position [°]
Reference: without decimal places
6Current actual volume flow rate [%]
Resolution: Vnom
Resolution: 0 – 10000
Volume flow rate actual value: 0.00 – 100.00%
7Actual volume flow rate in volume flow unit [m³/h], [l/s], [cfm] acc. Register 201RRAM
8Voltage at analogue input Y [mV]
Note: Connection terminal for analogue input Y not accessible with variant with connection socket
103Firmware versionR

0.00 – 100.00 %
104Status information
(Bit = 1 active, bit = 0 inactive)
Bit 5 mechanical overload
Bit 8 internal activity e.g. test run, adaptation
Bit 10 bus timeout monitoring triggered
105Operating range limitation: Operating parameter Vmin (qvmin) [%]
Resolution: Vnom
Resolution: 0 – 10000
Vmin: 0.00 – 100.00%
106Operating range limitation: Operating parameter Vmax (qvmax) [%]
Resolution: Vnom
Resolution: 0 – 10000
Vmax: 0.00 – 100.00%
108Behaviour in case of bus timeout; 0 = none; 1 = close; 2 = open; 3 = qvmin; 5 = qVmaxR, WEEPROM
109Definition of bus timeout [s]R, WEEPROM
120Definition of operating range: operating parameter Vmin (qvmin) in volume flow unit [m³/h], [l/s], [cfm] acc. register 201R, WEEPROM
121Definition of operating range: operating parameters Vmax (qvmax) in volume flow unit [m³/h], [l/s], [cfm] acc. Register 201R, WEEPROM
122Interface definition (Interface mode) For assignment see separate tableR, WEEPROM

130 *

Modbus address (device address)R, WEEPROM
201Volume flow unit 0 = l/s; 1 = m³/h; 6 = cfmR, WEEPROM
231Setting of mode:
Bit 0 defines the characteristic of the analogue interface.
Bit 0 = 0 characteristic: 0 – 10 V
Bit 0 = 1 characteristic: 2 – 10 V
Bit 4 defines the actual value signal as volume flow rate actual value or damper blade position.
Bit 4 = 0 volume flow rate actual value
Bit 4 = 1 Damper blade position
All other bits must not be changed.

Modbus parameter set, communication settings: baud rate, parity, stop bits, assignment see separate table

569Modbus communication settings: Modbus Response Time = 10 ms + delay; with delay= 3 ms × register value 0 – 255R, WEEPROM

* Factory setting: Modbus address 1

R = Register can be read

R,W = Register can be read and written

RAM = Volatile register value

EEPROM = Register value not volatile, but saved permanently (max. 1 million write processes)


Detailed information on register 122 (communication interface setpoint/actual value - Interface Mode)

Register value

Signal inputFeedback signal
Analogue (0) 2 – 10 V(0)2 – 10 V
2Modbus via Register 0Register 10
1Modbus via Register 0(0)2 – 10 V
3Analogue (0) 2 – 10 VRegister 10

Note: For the control component XS0-J6, only the register value 2 is practical, as the analogue input and the analogue feedback signal are not available on the connection socket.

Detailed information on register 568 (Modbus communication parameters)

Register value

Display setting valueBaud rateParityStop bits

15 **






** Factory setting: Modbus communication parameters

Range of display functions

Display functions

  • Volume flow rate actual value (unit optionally m³/h, l/s, cfm)
  • 3-character display with positional notation
  • Status and error display for various operating states, including display of activated override control, display of diagnostic function

Parameter setting

  • Adjustment option for the unit of the volume flow rate display m³/h, l/s, cfm
  • Adjustment option for the operating range qvmin, qvmax
  • For the variant with RJ12 connection socket, only the Modbus interface configuration is suitable
  • Adjustment option for Modbus communication settings (address, baud rate, stop bits, parity)


  • Activation of a test run
  • Activation of override controls Open, Closed, qvmin, qvmax, motor stop (note prioritisation)


  • After installation, wiring and connection of the supply voltage
  • Set the Modbus communication parameters via the integral display, the air terminal unit is then ready
  • Setpoint value default setting via X-AIRCONTROL
  • Comply with volume flow rate control range from 4 – 100 % of qvnom; do not set a volume flow rate which is below the minimum flow rate of the control unit
  • Only briefly remove the socket cover of the control component during wiring


Use and description of the display

Pressing the LED push button (< 3 s) selects the next menu item ① - ⑥. The selected menu item can be changed by pressing the LED push button for more than 3 s. Changing is done with the rotary selector switch. Pressing the LED push button again (< 3 s) confirms the selected value. If no entry is made for >= 60 s, the system returns to menu item 1.

Table 1: Description of the menu items

① FlowDisplay of actual values or operating states. Setting the volume flow rate unit m³/h, l/s, cfm.
② VminSetting qvmin
③ VmaxSetting qvmax


Displays the control signal and feedback signal alternately in [V],
Activation of override controls for test and diagnostic purposes:
tst = test run
oP = damper OPEN
cL = damper CLOSE
Lo = qvmin
Hi = qvmax
St = Motor stop
oFF = Override control Off
000 = Display firmware version


Selection of the operating mode:
CA0 = Setpoint value setting and actual value return via analogue interface (0 – 10 V)
CA2 = Setpoint value setting and actual value return via analogue interface (2 – 10 V)
CB2 = Setpoint value setting and actual value return via Modbus - Optional actual value return via (2 – 10 V)


Setting the modbus address: 1 - 247

and the baud rate, parity, stop bits: 1 (b1) - 32 (b32)

Description of status LEDs and error messages

LED flashing signalStatusDisplay
No supply voltage connected.

Inform TROX service technicians

Actuator overload detected (block)

Synchronisation after Power Up

Test mode activated

Overpressure sensor (overpressure)

Setpoint value or override control position not yet reached (display changes between e.g. Hi = High and actual value)

Override control position reached (display changes between e.g. Hi = High and actual value)

Normal operation with the setpoint being maintained. Signalled as long as the actuator does not rotate to readjust the setpoint value.

The flashing signal appears every 2 seconds. 1 = LED is illuminated, 0 = LED is not illuminated


product information


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