General Assist Technical Reference
Network Converter UTY-VTGX / UTY-VTGXV
Application, wiring, configuration and commissioning overview
For integrating compatible single-split and multi-split indoor units with a Fujitsu VRF control network
The UTY-VTGX and UTY-VTGXV allow compatible RAC and PAC indoor units to be operated and monitored from Fujitsu VRF central controllers. A wired remote controller may also be connected locally through the converter.
Installation requirement: Wiring, addressing and switch settings must be completed by appropriately qualified personnel using the current installation manual for the connected indoor unit, remote controller and network converter.
1. Purpose and model selection
One converter links one compatible single-split system, one compatible multi-split indoor-unit connection, or a grouped set of compatible single-split indoor units to the VRF transmission network.
| Model | Enclosure and supply | Wired remote controllers | Typical application |
|---|---|---|---|
| UTY-VTGX | Compact plastic enclosure; DC power supplied through the indoor-unit remote-controller circuit | Maximum 1 | Standard installations requiring one local wired controller |
| UTY-VTGXV | Metal enclosure; separate AC 208–240 V, 50/60 Hz supply | Maximum 2 | Applications requiring dual wired remote controllers |
Capacity limits: One converter can represent up to 16 compatible indoor units when they operate as one group. Up to 100 network converters may be included in one VRF network, subject to the total refrigerant-system limit of the control network.
2. Electrical and communication wiring
| Controller type | Indoor-unit connection | Remote-controller connection |
|---|---|---|
| Non-polar 2-wire | Connect to the converter terminal specified for the indoor-unit remote-controller circuit | Connect the wired controller to the same 2-wire control circuit as shown in the installation manual |
| Polar 3-wire | Connect the indoor unit to the designated indoor-unit terminals | Connect the wired controller to the designated Y1/Y2/Y3 remote-controller terminals, observing polarity |
- Connect the VRF transmission cable as a non-polar, two-conductor network in accordance with the applicable system manual.
- Do not bundle power wiring with transmission or remote-controller wiring.
- Use the specified cable type and earth the converter where required.
- Install indoors and route cables through the approved entry points only.
- Do not combine 2-wire and 3-wire remote controllers on the same converter.
3. Switch settings and addressing
| Setting | Purpose | Key point |
|---|---|---|
| SET 1 | Refrigerant-circuit or converter address | Each converter must have a unique valid address within the VRF network. |
| SET 2-1 | Transmission terminal resistance | Set only where the converter is at the required termination point. Do not enable unnecessary termination. |
| SET 3 | 2-wire or 3-wire remote-controller selection | The factory setting is normally 2-wire. Change it before power-up when a 3-wire controller is used. |
Addressing behaviour: Compatible 2-wire remote controllers can generally be recognised automatically. Polar 3-wire remote controllers require the applicable manual address configuration.
4. Available control functions
| Control point | Typical functions |
|---|---|
| VRF central controller | Start/stop, operating mode, temperature setting, fan speed where supported, filter indication reset and remote-controller restrictions. |
| Local wired remote controller | Start/stop, temperature setting, operating mode, fan speed, timer and other functions supported by the connected indoor unit. |
Supported functions depend on the connected indoor unit, remote controller and central controller. A command shown by the central controller may not be available if the RAC/PAC product does not support that function.
Remote-controller prohibition: Central prohibition commands apply to compatible wired remote controllers. A wireless remote controller cannot be physically locked through the converter in the same way.
5. Commissioning and connection verification
| 1 | Confirm the selected converter model is suitable for the required number and type of wired remote controllers. |
| 2 | Verify the connected indoor unit is listed as compatible with the network converter and wired-controller interface. |
| 3 | Check power supply, earthing, cable type, polarity for 3-wire controls and VRF transmission continuity. |
| 4 | Set the converter address, terminal resistance and 2-wire/3-wire selection before applying power. |
| 5 | Power the system and confirm local wired-controller operation. |
| 6 | Confirm every intended converter appears in the Service Tool or central-controller equipment list before completing the test run. |
| 7 | Test central start/stop, mode and set-temperature commands, then confirm status feedback is correct. |
6. Diagnostic LEDs and fault checks
LED1, LED2 and LED3 provide converter status and communication indications. Always compare the exact blink pattern with the error table in the current installation manual.
| Symptom | Checks |
|---|---|
| Converter not shown on the VRF network | Check converter power, VRF transmission wiring, duplicate addresses, address range and terminal-resistance setting. |
| Local controller does not operate | Confirm 2-wire/3-wire switch selection, controller compatibility, wiring terminals, polarity and controller address. |
| Central commands are incomplete | Confirm the requested function is supported by the connected RAC/PAC unit and controller combination. |
| Persistent internal communication fault | Power-cycle only after wiring and settings have been verified. If the communication circuit or microcontroller has failed, PCB replacement may be required. |
7. Important system restrictions
- Do not connect unrelated single-split or multi-split refrigerant systems through one converter.
- For a grouped single-split arrangement, all connected indoor units operate under the same command status.
- For individual control of indoor units in a multi-split system, a converter is required for each indoor unit connection.
- UTY-VTGX supports one wired remote controller only. Use UTY-VTGXV where two compatible wired controllers are required.
- Remote-controller cable length must remain within the limits stated in the applicable installation manual.
- Function settings through a remote controller depend on the selected 2-wire or 3-wire control architecture and connected product.
This article is a training overview. Always use the current installation instructions, design documentation and compatibility tables for the specific indoor unit, central controller and network converter.