XM0-J6 - Volume Current MODBUS, RJ12   | TROX GmbH
Compact controller XM0 for TVE and TVE-Q

Bus interface Modbus RTU


X-AIRCONTROL zone module Modbus


RJ12 socket


Control component for type TVE



Control component with dynamic transducer and Modbus RTU interface for X-AIRCONTROL

Compact device for use with VAV terminal units TVE

  • Controller, dynamic differential pressure transducer and actuator in one casing
  • Use in ventilation and air conditioning systems, only with clean 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
  • Dynamic differential pressure transducer, electronic controller, and actuator are fitted together in one casing
  • Choice of various control options based on setpoint value default setting
  • Suitable for X-AIRCONTROL room control, Modbus zone module
  • Variable flow rate control is based on setpoint values received via the communication interface from a temperature, humidity or air quality circuit, for example
  • Simple connection of both supply voltage and network with just one RJ12 connection socket
  • Override controls for activating qvmin, qvmax, shut-off and OPEN is possible using the Modbus register
  • The volume flow rate actual value is available as a network data point
  • The damper blade position is available as a network data point
  • Standard filtration in comfort conditioning systems allows for use of the controller in the supply air without additional dust protection

With heavy dust levels in the room

  • Install suitable extract air filters upstream, as a partial volume flow is routed through the transducer for volume flow rate measurement

If the air is contaminated with dust, fluff or sticky particles

  • Use of the XS0-J6 module instead of the XM0-J6 compact controller described here

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 dynamic pressure measurements
  • Overload protection
  • Connection socket RJ12 with cover
  • Display and control elements for easy menu navigation
  • Menu navigation allows for adjusting operating parameters and the communication interface
  • Service interface


  • TROVM-024T-05I-DD15-MB with plug connection RJ12
  • Can only be used for type TVE


  • As the volume flow rates are factory set, the terminal units have to be installed at the specified locations
  • Network integration requires commissioning steps
  • Operating parameters can be adjusted by others (using the display and control elements, an adjustment device or the 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 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


  • Dynamic transmitter for clean 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 reading and writing of 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 the VAV terminal unit are factory set
  • Operating values: qvmin, qvmax are factory set 
  • Values can be adjusted at a later stage, using either the display and the control elements on the controller or optional tools: adjustment device, PC software (wire connection in each case), or in Modbus mode also by 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 / XM0-J6 / M / qvminqvmaxm³/h

1 Type
TVE VAV terminal unit 

2 Acoustic cladding
No entry: none
D With acoustic cladding 

3 Material

Galvanised sheet steel (standard construction

P1 Powder-coated RAL 7001, silver grey

A2 Stainless steel construction 

5 Nominal size [mm]
100, 125, 160, 200, 250, 315, 400 

6 Accessories

No entry: none
D2 Double lip seal both ends
G2 Matching flanges for both ends

7 Attachments (control components)
XM0-J6 Compact controller with dynamic transducer, Modbus RTU, display, RJ12 socket 

8 Operating mode
M Modbus RTU 

9 Operating values for factory setting
Volume flow rates in m³/h or l/s

10 Volume flow rate unit

Order example: TVE/100/D2/XM0-J6/M/20-350 m³/h
Acoustic claddingNone
MaterialGalvanised sheet steel
Nominal size100 mm
AccessoriesDouble lip seal both sides
AttachmentCompact controller Modbus, dynamic transducer, for X-AIRCONTROL
Operating modeModbus RTU
Volume flow rate20 – 350 m³/h






Product details, Technical data


Compact controllers for VAV terminal units

VAV terminal units

Type of installation component

Part number






Compact controller TROVM-024T-05I-DD15-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
Power consumption (when running/when idle)

1 W

Run time for 90°100 s
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 XM0-J6. For this reason, the configuration register 122 (interface mode) must not be changed by others. To use an analogue interface, the variant XM0 must be used.


Communication interface Modbus RTU (operating mode M)



Access right


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

Definition of operating range: operating parameters Vmin (qvmin) in volume flow rate unit [m³/h], [l/s], [cfm] according to register 201

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 input

Feedback signal

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

Note: Only register value 2 makes sense for control component XS0-J6 because the connection socket cannot be used as analogue input or for an analogue feedback signal.


Detailed information on register 568 (Modbus communication parameters)

Register value

Display setting value

Baud rate


Stop 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
  • Selection of the interface configuration Modbus or analogue including signal voltage range 0 – 10 V or 2 – 10 V DC
  • Adjustment option for Modbus communication settings (address, baud rate, stop bits, parity)


Diagnosis functions

  • Activation of a test run
  • Activation of override controls Open, Closed, qvmin, qvmax, motor stop (note prioritisation)
  • Display of the voltage value on the analogue input

After installation, wiring and connection of the supply voltage

  • When using the Modbus interface: set the Modbus communication parameters using the integral display, the air terminal unit is then ready
  • Setpoint value default setting via Modbus register
  • When using the analogue interface: air terminal unit is immediately ready for use
  • 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 protective cap 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 details


Modbus operation (operating mode M in the order code)

A smooth exchange of data in the Modbus RTU network (network by others) requires that the communication parameters and the user address for the Modbus interface are set.
The interface offers standardised Modbus register access to the available data points by means of the ReadHoldingRegister (3) and WriteSingleRegister (6) functions.


Setpoint value default setting

  • With operating mode M, the setpoint value defaults as a percentage [%] in Modbus register 0.
  • The percentage value refers to the volume flow rate range qvmin – qvmax
  • Volume flow rate range qvmin – qvmax is set in the factory according to the order code
  • q vmin or q vmax can be adjusted at a later stage using the setup menu (display), an adjustment device, the Modbus interface or X-AIRCONTROL


Actual value retrieval

  • The volume flow rate actual value can be retrieved using the display, an adjustment device or X-AIRCONTROL
  • X-AIRCONTROL allows you to retrieve also other data in addition to the volume flow rate actual value


Override control

If necessary, and depending on the situation, the volume flow controller can be set to a special operating mode (override control)
The following modes are available: control based on qvmin, control based on qvmax, damper blade OPEN or damper blade CLOSED

  • Values default via X-AIRCONTROL
  • Override control for bus timeout monitoring:
  • If the communication fails, the controller goes into the status that was last saved (factory setting) Using suitable software, the factory setting can be changed in Modbus register 108 Any communication will reset the timeout of the bus failure monitoring system

Override controls for diagnosis
You can enable these override controls on the diagnosis menu (controller display) or with X-AIRCONTROL


Priority of various default setting options
Service tool defaults have priority over Modbus defaults

  • Highest priority: defaults coming from a service tool (service connector), e.g. adjustment device or PC software, for test purposes
  • Lowest priority: defaults coming from Modbus 1 or the diagnosis menu on the controller



product information


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Our department for Service-Requests will contact you asap.
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